CBSE Class 10 Science — Metals and Non-metals

Which of the following is an amphoteric oxide?

Which of the following is a poor conductor of electricity?

On reaction with dilute HCl, which of the following pair of metals will evolve hydrogen gas?

When an element 'X' reacts with water, it starts floating. Identify the element 'X':

(a) What are amphoteric oxides? (b) Categorise the following based on their nature: $\mathrm{ZnO,Na_2O,CO_2}$

Read the following passage and answer the questions given below: Most of metals occur in combined state in form of ores. Carbonate ores are converted into oxides by calcination and sulphide ores by roasting. Oxides are reduced with suitable reducing agent like carbon to get free metal. Highly reactive metals like Al, Mg are also used as reducing agents to obtain metal from their oxides. Most reactive metals are obtained by electrolytic reduction of their molten ores. Alloying is a very good method of improving the properties of a metal. We can get desired properties by this method. The electrical conductivity and melting point of an alloy is less than that of pure metals. (a) Why carbonate or sulphide ores are converted to oxides before extraction of metal from it? (b) Write a reaction in which Aluminium is used as a reducing agent to obtain metal from its oxide. (c) (i) How is copper obtained from its ore ($\mathrm{Cu_2S}$)? Give equations of the reactions. OR (c) (ii) (I) Why highly reactive metals cannot be obtained from their oxides by using carbon as a reducing agent? (II) Why solder, an alloy of lead and tin, is used for welding electrical wires together?

(A) (i) Give reasons for the following: (I) Ionic compound have generally high melting points and boiling points. (II) Solder, an alloy of lead and tin, is used for welding electrical wires. (III) Carbon cannot reduce the oxides of Na or Mg. (ii) The reaction of compound 'X' with aluminium is used to join railway tracks: (I) Identify the compound 'X'. (II) Name the reaction. (III) Write the balanced chemical equation of the reaction of compound 'X' with aluminium. OR (B) (i) Write the balanced chemical equations when: (I) A mixture of $Cu_2O$ and $Cu_2S$ is heated. (II) $ZnS$ is heated in the presence of oxygen. (ii) Give reasons for the following: (I) The wires carrying current in homes have a coating of PVC. (II) To make hot water tanks, copper is used and not steel. (iii) Show the formation of ionic compound $CaO$ with electron dot structure. [Atomic number: $Ca = 20, O = 8$]

Attempt either option (A) or (B): (A) (i) Give reasons for the following: (I) Ionic compounds have generally high melting points and boiling points. (II) Solder, an alloy of lead and tin, is used for welding electrical wires. (III) Carbon cannot reduce the oxides of Na or Mg. (ii) The reaction of compound 'X' with aluminium is used to join railway tracks: (I) Identify the compound 'X'. (II) Name the reaction. (III) Write the balanced chemical equation of the reaction of compound 'X' with aluminium. [3+2] OR (B) (i) Write the balanced chemical equations when: (I) A mixture of $Cu_2O$ and $Cu_2S$ is heated. (II) $ZnS$ is heated in the presence of oxygen. (ii) Give reasons for the following: (I) The wires carrying current in homes have a coating of PVC. (II) To make hot water tanks, copper is used and not steel. (iii) Show the formation of ionic compound $CaO$ with electron dot structure. [Atomic number: $Ca = 20$, $O = 8$] [2+2+1]

The products formed when Aluminium and Magnesium are burnt in the presence of air respectively are :

A metal, M, displaces iron from aqueous solution of ferrous sulphate but fails to do so in case of aqueous solution of aluminium sulphate. The metal M is

The property by virtue of which a solid material can be drawn into thin wires is called :

The most common method of extraction of metals from their oxide ores is :

Select from the following a statement which is not true about burning of magnesium ribbon in air:

Aluminium powder is used in thermit welding because:

A metal, 'X', on treatment with sodium hydroxide liberates a gas 'G'. It also liberates the same gas, 'G' on treatment with dilute sulphuric acid. Based on above information, 'X' and 'G' respectively are

The colour of the solution observed after about 1 hour of placing iron nails in copper sulphate solution is:

Two metals zinc and tin are dissolved separately in definite proportions in molten copper (the primary metal) to obtain two different alloys respectively known as:

Reaction between two elements A and B, forms a compound C. A loses electrons and B gains electrons. Which one of the following properties will not be shown by compound C ?

The metals obtained from their molten chlorides by the process of electrolytic reduction are :

During electrolytic refining of copper, the anode, the cathode and the electrolyte used respectively are

The formation of magnesium oxide is correctly shown in option :

For Questions number 17 to 20, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true. Assertion (A): The metals high up in the reactivity series cannot be obtained from their compounds by heating with carbon. Reason (R): Displacement reactions can also be used to obtain metal.

For Questions number 17 to 20, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below. Assertion (A): Hydrogen gas is not evolved when a metal reacts with nitric acid. Reason (R): Nitric acid is a strong reducing agent and reduces the hydrogen produced in the reaction to water.

(a) In common practice silver is recovered from silver nitrate solution by the use of copper metal. Name the type of reaction that takes place in this process and give the chemical equation of the reaction involved. (b) Name the method used for refining silver.

(A) Show the formation of magnesium chloride by electron transfer. Write the name of the cation and anion present in the compound formed. (Atomic Number of $Mg = 12$, $Cl = 17$) OR (B) How is zinc extracted from its ore? Name the processes involved in the extraction and write chemical equations for the reactions that occur during these processes.

(a) What is a reactivity series of elements? How is it developed? Arrange the following elements as they are arranged in the reactivity series: Aluminum, Calcium, Copper, Lead (b) Write balanced chemical equation to show the reaction of iron (III) oxide ($\mathrm{Fe_2O_3}$) with aluminium.

(a) "Displacement reactions also play a key role in extracting metals in the middle of the reactivity series." Justify this statement with two examples. (b) Why can metals high up in the reactivity series not be obtained by reduction of their oxides by carbon?

Design an activity to show that metals are good conductors of heat and have high melting points.

(a) With the help of an activity, explain the conditions under which iron articles get rusted. OR (b) (i) Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water. (ii) Write a test to identify the gas evolved (if any) during the reaction of these metals with water.

Write the electron-dot structures of (i) sodium, and (ii) oxygen. Using these structures, show the formation of sodium oxide. Mark the anion and cation present in this compound. (At. No. - Sodium = 11 and Oxygen = 8)

(a) (i) Consider the following metals: K, Ca, Al, Cu, Ag, Fe Select from the above metals, a metal which I. does not react with oxygen even at high temperature. II. reacts with oxygen at ordinary temperature and forms a protective oxide layer which prevents the metal from further oxidation. III. catches fire when kept in the open. IV. does not burn in oxygen but the hot metal is coated with a black coloured oxide layer. (ii) What are amphoteric oxides? With the help of balanced chemical equations show that aluminium oxide is an amphoteric oxide. (iii) What are alkalis? Give one example. OR (b) (i) With the help of balanced chemical equations state the process of extracting (I) mercury from its ore called cinnabar, and (II) copper from its sulphide ore. (ii) Silver and copper articles slowly lose their shiny surfaces when exposed to air. Name the compounds formed on (I) silver articles, and (II) copper articles in the form of coating.

Many pure metals like copper, iron and gold are very soft and as such are considered unsuitable for certain uses. Metallic objects around us such as cooking utensils, statues, ornaments, guns etc. are actually not made up of pure metals. Instead of pure metals, alloys are used in the design of most of the useful objects. Making alloys enhances the basic properties of a metal which is the primary constituent (metal) of an alloy. (I) How does electrical conductivity and melting point of a metal change when it is converted to its alloy by mixing a small amount of an element in it? (II) Name an alloy used for welding two wires together in an electric circuit. Write its major constituents. (III) (a) What are alloys? How is 'Brass' (an alloy) prepared? OR (III) (b) What is stainless steel? How is it prepared? Write one important property which makes it more useful in making cooking utensils as compared to its primary metal.

The oxide which can react with $\mathrm{HCl}$ as well as $\mathrm{KOH}$ to give corresponding salt and water is

The metals which are found in both free state as well as combined state are:

Consider the following cases : (a) $\mathrm{CaSO}_4 + \mathrm{Al} \longrightarrow$ (b) $\mathrm{CuSO}_4 + \mathrm{Ca} \longrightarrow$ (c) $\mathrm{FeSO}_4 + \mathrm{Cu} \longrightarrow$ (d) $\mathrm{ZnSO}_4 + \mathrm{Mg} \longrightarrow$ The cases in which new products will form are -

A metal 'X' is used in thermit process. When 'X' is heated with oxygen, it gives an oxide 'Y', which is amphoteric in nature. 'X' and 'Y' respectively are :

Oxides of aluminium and zinc are :

Assertion (A): The extraction of metals from their sulphide ores cannot take place without roasting of the ore. Reason (R): Roasting converts sulphide ores directly into metals.

Assertion (A): A piece of Zinc metal gets reddish brown coating when kept in copper sulphate solution for some time. Reason (R): Copper is more reactive metal than Zinc.

Assertion (A) : Different metals have different reactivities with water and dilute acids. Reason (R) : Extraction of a metal from its ore depends on its position in the reactivity series.

State reasons for the following: (a) Zinc oxide is an amphoteric oxide. (b) Sodium metal is stored in bottle filled with kerosene oil. (c) In the reactions of nitric acid with metals, generally hydrogen gas is not evolved.

It is observed that Calcium on reaction with water floats on its surface. Explain why it happens. Also write a balanced chemical equation for the reaction that occurs. What happens when the aqueous solution of the product of this reaction reacts with Carbon dioxide gas? Write a balanced chemical equation for the reaction.

(a) State giving reason the reduction process to obtain the following metals from their compounds: (i) Mercury, (ii) Copper and (iii) Sodium. OR (b) State giving reason for the change in appearance observed when each of the following metal is exposed to atmospheric air for some time: (i) Silver, (ii) Copper and (iii) Iron.

Draw a labelled diagram to show electrolytic refining of copper. State what happens when electric current is passed through the electrolyte taken in this case.

Name the ore of mercury and state the form in which it is found in nature. Write the chemical equations along with the condition required for the reactions involved in the extraction of mercury from its ore.

Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded. Answer the following questions : (a) When activity was done with dilute hydrochloric acid, then in which one of the test tubes was the rate of formation of bubbles the fastest and the thermometer showed the highest temperature ? (b) Which metal did not react with dilute hydrochloric acid ? Give reason. (c) (i) Why is hydrogen gas not evolved when a metal reacts with dilute nitric acid ? Name the ultimate products formed in the reaction. OR (c) (ii) Name the type of reaction on the basis of which reactivity of metals is decided. You have two metals X and Y. How would you decide which is more reactive than the other ?

Metal oxides generally react with acids, but few oxides of metal also react with bases. Such metallic oxides are : I. MgO II. ZnO III. $Al_2O_3$ IV. CaO

A metal 'X' is used in thermite process. When X is burnt in air it gives an amphoteric oxide 'Y'. 'X' and 'Y' are respectively:

Which of the following statements is true for an amphoteric oxide ?

Among the following, the metal with lowest density is :

The number of electrons in the outermost shell of the atom of a non-metal can be :

Bronze is an alloy of

Assertion (A) : In the following reaction $\mathrm{ZnO + C\longrightarrow Zn + CO}$. Reason (R) : Carbon is a reducing agent that reduces ZnO to Zn.

(a) A substance 'X' is used as a building material and is insoluble in water. When it reacts with dil. $HCl$, it produces a gas which turns lime water milky. (i) Write the chemical name and formula of 'X'. (ii) Write chemical equations for the chemical reactions involved in the above statements. OR (b) A metal 'M' on reacting with dilute acid liberates a gas 'G'. The same metal also liberates gas 'G' when reacts with a base. (i) Write the name of gas 'G'. (ii) How will you test the presence of this gas ? (iii) Write chemical equations for the reactions of the metal with (1) an acid and (2) a base.

Metals are required for a variety of purposes. For this we need their extraction from their ores. Ores mined from the earth are usually contaminated with many impurities which must be removed prior to the extraction of metals. The extraction of pure metal involves the following steps: (1) Concentration of ore (2) Extraction of the metal from the concentrated ore (3) Refining of the metal (a) Name an ore of Mercury and state the form in which Mercury is present in it. (b) What happens to zinc carbonate when it is heated strongly in a limited supply of air? (c) The reaction of a metal A with $\mathrm{Fe}_2\mathrm{O}_3$ is highly exothermic and is used to join railway tracks. (I) Identify the metal A and name the reaction taking place. (II) Write the chemical equation for the reaction of metal A with $\mathrm{Fe}_2\mathrm{O}_3$. OR (c) We cannot use carbon to obtain sodium from sodium oxide. Why? State the reactions taking place at cathode and anode during electrolytic reduction of sodium chloride.

On the basis of reactivity metals are grouped into three categories - (i) Metals of low reactivity (ii) Metals of medium reactivity (iii) Metals of high reactivity. Therefore metals are extracted in pure form from their ores on the basis of their chemical properties. Metals of high reactivity are extracted from their ores by electrolysis of the molten ore. Metals of low reactivity are extracted from their sulphide ores, which are converted into their oxides. The oxides of these metals are reduced to metals by simple heating. (a) Name the process of reduction used for a metal that gives vigorous reaction with air and water both. (b) Carbon cannot be used as a reducing agent to obtain aluminium from its oxide? Why? (c) Describe briefly the method to obtain mercury from cinnabar. Write the chemical equation for the reactions involved in the process. OR (c) Differentiate between roasting and calcination giving chemical equation for each.

Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic in nature. But some metal oxides show both basic as well as acidic behaviour. Different metals show different reactivities towards oxygen. Some react vigorously while some do not react at all. (a) What happens when copper is heated in air? (Give the equation of the reaction involved). (b) Why are some metal oxides categorized as amphoteric? Give one example. (c) Complete the following equations: (i) $\mathrm{Na_2O_{(s)} + H_2O_{(l)} \rightarrow}$ (ii) $\mathrm{Al_2O_3 + 2NaOH \rightarrow}$ OR (c) On burning Sulphur in oxygen a colourless gas is produced. (i) Write chemical equation for the reaction. (ii) Name the gas formed. (iii) State the nature of the gas. (iv) What will be the action of this on a dry litmus paper?

The melting points and boiling points of some ionic compounds are given below : | Compound | Melting Point (K) | Boiling Point (K) | | :--- | :--- | :--- | | NaCl | 1074 | 1686 | | LiCl | 887 | 1600 | | CaCl2 | 1045 | 1900 | | CaO | 2850 | 3120 | | MgCl2 | 981 | 1685 | These compounds are termed ionic because they are formed by the transfer of electrons from a metal to a non-metal. The electron transfer in such compounds is controlled by the electronic configuration of the elements involved. Every element tends to attain a completely filled valence shell of its nearest noble gas or a stable octet. (i) Show the electron transfer in the formation of magnesium chloride. (1 mark) (ii) List two properties of ionic compounds other than their high melting and boiling points. (1 mark) (iii) (A) While forming an ionic compound say sodium chloride how does sodium atom attain its stable configuration ? (2 marks) OR (iii) (B) Give reasons : (i) Why do ionic compounds in the solid state not conduct electricity ? (ii) What happens at the cathode when electricity is passed through an aqueous solution of sodium chloride ? (2 marks)

Explain giving reason why although the nuclear charge in atoms increases in moving from left to right in a period as well as in moving from top to bottom in a group in the Modern periodic table, but the size of the atoms does not vary similarly in both situations.

The atomic number of an element 'X' is 11. (i) Write the electronic configurations of X and find its valency. (ii) Write the formula and nature of its oxide.

The electrons in the atoms of two elements X and Y are distributed in three shells having 1 and 7 electrons respectively in their outermost shells. (a) Write the group numbers of these elements in the Modern Periodic Table. (b) Write the molecular formula of the compound formed when X and Y combine with each other. (c) Which of the two is electropositive ?

State the criteria used by Mendeleev for creating his Periodic Table. Compare the position of isotopes of elements in the Mendeleev's Periodic Table and in the Modern Periodic Table.

(a) State Newland Law of Octaves. (b) With an example, explain Dobereiner's Triads. (c) List one limitation each of both the attempts mentioned in 'a' & 'b'.

Name the elements whose compounds formed the basis of classification in Mendeleev's periodic table. Why did Mendeleev choose these elements? How the formulae of these compounds had helped Mendeleev in deciding the position of an element in his periodic table?

(a) List two advantages of adopting the atomic number of an element as the basis of classification of elements in the Modern Periodic Table. (b) Write the electronic configurations of the elements X (atomic number 13) and Y (atomic number 20).

In the following table, some elements have been arranged in a certain pattern: | sa (do) | re (re) | ga (mi) | ma (fa) | pa (so) | da (la) | ni (ti) | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | H | Li | Be | B | C | N | O | | F | Na | Mg | Al | Si | P | S | | Cl | K | Ca | Cr | Ti | Mn | Fe | | Co and Ni | Cu | Zn | Y | In | As | Se | | Br | Rb | Sr | Ce and La | Zr | - | - | Identify the periodic law with which the given table is associated. List two important features and two anomalies of the above periodic law.

OR State the Periodic Law on which the Modern Periodic Table is based.

How many metals are present in second period of periodic table?

Define electropositivity. OR The atomic radii of first group elements are given below: | Group-I element | Atomic Radii (pm) | | :--- | :--- | | Na | 86 | | K | 231 | | Rb | 244 | | Cs | 282 | State the reason behind the observed trend in the above elements.

State the common characteristic of the following elements : Boron, Silicon, Germanium and Arsenic

OR An element X is forming acidic oxide. Its most probable position in the modern periodic table is

An element X with atomic number 12 forms a compound with element Y with atomic number 17. The formula of the compound formed is

An element 'X' with atomic number 11 forms a compound with element 'Y' with atomic number 8. The formula of the compound formed is

On the basis of electronic configuration of $\frac{9}{5}\mathrm{X}$, the group number and period of the element 'X' is:

An element 'X' is forming an acidic oxide. Its position in modern periodic table will be OR Consider the following statements about an element 'X' with number of protons 13. (A) It forms amphoteric oxide (B) Its valency is three (C) The formula of its chloride is $\text{XCl}_3$ The correct statement(s) is/are

Assertion (A) : The metals and alloys are good conductors of electricity. Reason (R) : Bronze is an alloy of copper and tin and it is not a good conductor of electricity.

List three differentiating features between the processes of galvanisation and alloying. OR Compare in tabular form the reactivities of the following metals with cold and hot water: (a) Sodium (b) Calcium (c) Magnesium

From the elements Li, K, Mg, C, Al, S identify the (a) elements belonging to the same group. (b) element which has the tendency to lose two electrons. (c) element which prefers sharing of electrons to complete its octet. (d) most metallic element. (e) element that forms acidic oxide. (f) element that belongs to group 13.

Study the data of the following three categories A, B and C. | Category | Name of the element | Atomic Mass | | :--- | :--- | :--- | | A | Li | 7 | | | Na | 23 | | | K | 39 | | B | N | 14 | | | P | 31 | | | As | 74 | | C | B | 10.8 | | | Al | 27 | | | Ga | 69.7 | (i) From the given three categories A, B and C, pick the one which forms Dobereiner's Triads. (ii) Why did Mendeleev placed elements of category A, B and C in three different groups? (iii) Is Newland law of octaves applicable to all the three categories? Give reason to justify your answer.

From the elements $^{39}_{19}\mathrm{A}$, $^{28}_{14}\mathrm{B}$, $^{16}_{8}\mathrm{C}$ and $^{40}_{18}\mathrm{D}$ identify: (a) the most electro positive element. (b) a noble gas. (c) a metalloid. (d) an element which will gain 2 electrons to attain nearest noble gas configuration. (e) formula of compound formed between A and C. (f) elements belonging to same period.

(a) How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle? Why cannot the same process be applied for them? Name and explain the process of extraction of sodium. (b) Draw a labelled diagram of electrolytic refining of copper.

Carbon cannot reduce the oxides of sodium, magnesium and aluminium to their respective metals. Why? Where are these metals placed in the reactivity series? How are these metals obtained from their ores? Take an example to explain the process of extraction along with chemical equations.

Two ores X and Y were taken. On heating these ores it was observed that (a) ore X gives $CO_2$ gas, and (b) ore Y gives $SO_2$ gas. Write steps to convert these ores into metals, giving chemical equations of the reactions that take place.

Write balanced chemical equations to explain what happens, when: (i) Mercuric oxide is heated. (ii) Mixture of cuprous oxide and cuprous sulphide is heated. (iii) Aluminium is reacted with manganese dioxide. (iv) Ferric oxide is reduced with aluminium. (v) Zinc carbonate undergoes calcination. OR (i) By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify the ions present in this compound. (ii) Ionic compounds are solids. Give reasons. (iii) With the help of a labelled diagram show the experimental set up of action of steam on a metal.

OR: What happens when (Write the balanced equation involved) - (i) Copper is heated in air? (ii) Aluminium oxide is reacted with hydrochloric acid? (iii) Potassium reacts with water? (iv) Cinnabar is heated in air? (v) Aluminium oxide reacts with sodium hydroxide?

OR (a) With the help of a diagram explain the method of refining of copper by electrolysis. (b) How are broken railway tracks joined? Give the name of the process and the chemical equation of the reaction involved.

The position of certain elements in the Modern Periodic Table are shown below. | Group | 1 | 2 | 3 to 12 | 13 | 14 | 15 | 16 | 17 | 18 | | :--- | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | | **Period 1** | G | | | | | | | | H | | **Period 2** | A | | | I | | | B | | C | | **Period 3** | | D | | | E | | | | F | Using the above table answer the following questions giving reasons in each case: (i) Which element will form only covalent compounds? (ii) Which element is a non-metal with valency 2? (iii) Which element is a metal with valency 2? (iv) Out of H, C and F which has largest atomic size? (v) To which family does H, C and F belong?

OR Define atomic size. Give its unit of measurement. In the modern periodic table what trend is observed in the atomic radius in a group and a period and why is it so?

(a) (i) Write two properties of gold which make it the most suitable metal for ornaments. (ii) Name two metals which are the best conductors of heat. (iii) Name two metals which melt when you keep them on your palm. (b) Explain the formation of ionic compound CaO with electron-dot structure. Atomic numbers of calcium and oxygen are 20 and 8 respectively.

(a) Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores. (b) How is copper extracted from its sulphide ore? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper.

(a) The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts. (b) Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass. (c) State Modern periodic law.

A student added few pieces of aluminium metal to two test tubes A and B containing aqueous solutions of iron sulphate and copper sulphate. In the second part of her experiment, she added iron metal to another test tubes C and D containing aqueous solutions of aluminium sulphate and copper sulphate. In which test tube or test tubes will she observe colour change? On the basis of this experiment, state which one is the most reactive metal and why.

Na, Mg and Al are the elements of the 3rd period of the Modern Periodic Table having group number 1, 2 and 13 respectively. Which one of these elements has the (a) highest valency, (b) largest atomic radius, and (c) maximum chemical reactivity? Justify your answer stating the reason for each.

What is periodicity in properties of elements with reference to the Modern Periodic Table? Why do all the elements of the same group have similar properties? How does the tendency of elements to gain electrons change as we move from left to right in a period? State the reason of this change.

Write the number of periods and groups in the Modern Periodic Table. How does the metallic character of elements vary on moving (i) from left to right in a period, and (ii) down a group ? Give reason to justify your answer.

Write the electronic configuration of two elements X and Y whose atomic numbers are 20 and 17 respectively. Write the molecular formula of the compound formed when element X reacts with element Y. Draw electron-dot structure of the product and also state the nature of the bond formed between both the elements.

(a) Determine the number of valence electrons and the valency of ‘X’. (b) Molecular formula of the compound when ‘X’ reacts with hydrogen and write its electron dot structure. (c) Name the element ‘X’ and state whether it is metallic or non-metallic. An element ‘X’ has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of ‘X’. Also write group number, period number and valency of ‘X’.

The position of eight elements in the Modern Periodic Table is given below where atomic numbers of elements are given in the parenthesis. | Period No. | | | |---|---|---| | 2 | Li (3) | Be (4) | | 3 | Na (11) | Mg (12) | | 4 | K (19) | Ca (20) | | 5 | Rb (37) | Sr (38) | (i) Write the electronic configuration of Ca. (ii) Predict the number of valence electrons in Rb. (iii) What is the number of shells in Sr? (iv) Predict whether K is a metal or a non-metal. (v) Which one of these elements has the largest atom in size? (vi) Arrange Be, Ca, Mg and Rb in the increasing order of the size of their respective atoms.

An element ‘X’ belong to 3rd period and group 13 of the Modern Periodic Table. (a) Determine the valence electrons and the valency of ‘X’. (b) Molecular formula of the compound formed when ‘X’ reacts with an element ‘Y’ (atomic number = 8). (c) Write the name and formula of the compound formed when ‘X’ combines with chlorine.

An element ‘X’ belongs to 3rd period and group 16 of the Modern Periodic Table. (a) Determine the number of valence electrons and the valency of ‘X’. (b) Molecular formula of the compound when ‘X’ reacts with hydrogen and write its electron dot structure. (c) Name the element ‘X’ and state whether it is metallic or non-metallic.

An element ‘X’ has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of ‘X’. Also write group number, period number and valency of ‘X’.

Three elements ‘X’, ‘Y’ and ‘Z’ have atomic numbers 7, 8 and 9 respectively. (a) State their positions (Group number and period number both) in the Modern Periodic Table. (b) Arrange these elements in the decreasing order of their atomic radii. (c) Write the formula of the compound formed when ‘X’ combines with ‘Z’.

How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move: (a) down a group and (b) from left to right in a period

From the following elements: $4 \text{Be}; 9 \text{F}; 19 \text{K}; 20 \text{Ca}$ (i) Select the element having one electron in the outermost shell. (ii) two elements of the same group. Write the formula of and mention the nature of the compound formed by the union of 19K and element X(2,8,7).

State reason for the following: (i) Lemon is used for restoring the shine of tarnished copper vessels. (ii) A metal sulphide is converted into its oxide to extract the metal from the sulphide ore. (iii) Copper wires are used in electrical connections.

(a) Define corrosion. (b) What is corrosion of iron called? (c) How will you recognise the corrosion of silver? (d) Why corrosion of iron is a serious problem? (e) How can we prevent corrosion?

Mrignayani was doing the experiment of comparing reactivity of metals in the laboratory. She was given aluminium metal and was told to check reactivity by using four solutions (A, B, C, and D, where A is aluminium sulphate). She would observe that reaction takes place in:

How many vertical columns are there in the modern periodic table and what are they called?

Given below are some elements of the modern periodic table: $4Be, 9Fe, 14Si, 19K, 20Ca$. (i) Select the element that has one electron in the outermost shell and write its electronic configuration. (ii) Select two elements that belong to the same group. Give reason for your answer. (iii) Select two elements that belong to the same period. Which one of the two has bigger atomic size?

Write the number of periods the modern periodic table has. How do the valency and metallic character of elements vary on moving from left to right in a period? How do the valency and atomic size of elements vary down a group?

How can the valency of an element be determined if its electronic configuration is known ? What will be the valency of an element of atomic number 9 (nine) ?

Choose from the following : $6C, 8O, 10Ne, 11Na, 14Si$ (i) Elements that should be in the same period. (ii) Elements that should be in the same group. State reason for your selection in each case.

Consider the following elements: $4\text{Be}, 9\text{F}, 19\text{K}, 20\text{Ca}$. Choose from the following: (i) The element having one electron in the outermost shell. (ii) Two elements of the same group.

An element has atomic number 13. (a) What is the group and period number to which this element belongs? (b) Is this element a metal or a non-metal? Justify your answer.

An element 'X' has atomic number 13 : (a) Write its electron configuration. (b) State the group to which 'X' belongs ? (c) Is 'X' a metal or a non-metal ? (d) Write the formula of its bromide.

An element 'X' belongs to 3rd period and group 17 of the periodic table. State its (i) electronic configuration, (ii) valency. Justify your answer with reasoning.

Na, Mg and Al are the elements having one, two and three valence electrons respectively. Which of these elements (i) has the largest atomic radius, (ii) is least reactive ? Justify your answer stating reason for each.

F, Cl and Br are the elements each having seven valence electrons. Which of these (i) has the largest atomic radius, (ii) is most reactive? Justify your answer stating reason for each.

(a) How many periods are there in the modern periodic table of elements? (b) How do atomic radius, valency and metallic character vary down a group? (c) How do the atomic size and metallic character of elements vary as we move from left to right in a period?

The aqueous solutions of copper sulphate and zinc sulphate appear

A student puts one big iron screw each in four test tubes containing aqueous solutions of aluminium sulphate, copper sulphate, ferrous sulphate and zinc sulphate. After some time he observed a reddish brown coating only on the surface of the screw which was put in the solution of

In the periodic table, how does the tendency of atoms to lose electrons change on going from (i) left to right across a period ? (ii) top to bottom in a group ?

(i) How do you calculate the possible valency of an element from the electronic configuration of its atoms? (ii) Calculate the valency of an element X whose atomic number is 9.

What is meant by periodicity of properties of elements ? Why are the properties of elements placed in the same group of the periodic table similar ?

How does the electronic configuration of an atom of an element relate to its position in the modern periodic table? Explain with one example.

The positions of three elements A, B and C in the periodic table are indicated below : | | Group 16 | Group 17 | |---|---|---| | First Period | — | — | | Second Period | — | A | | Third Period | — | — | | Fourth Period | B | C | (a) State whether element C would be a metal or a non-metal. Why ? (b) Which is the more active element, A or C ? Why ? (c) Which type of ion (cation or anion) will be formed by the element C ? Why ?

On adding a clean Aluminium strip to an aqueous solution of copper sulphate, it is observed that the colour of the solution changes from ______.

The colour of an aqueous solution of zinc sulphate as observed in the laboratory is:

An aqueous solution of zinc sulphate was taken in four test tubes. Zinc, Iron, Copper and Aluminium pieces were dropped into separate test tubes as given below : I (Zn), II (Fe), III (Cu), IV (Al). A reaction will be observed in test tubes

To show that zinc is a more active metal than copper, the correct procedure is to:

Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells but different number of electrons in their outermost shell. It was found that elements A and G combine to form an ionic compound. This compound is added in a small amount to almost all vegetable dishes during cooking. Oxides of elements A and B are basic in nature while those of E and F are acidic. The oxide of D is almost neutral. Based on the above information answer the following questions : (i) To which group or period of the periodic table do the listed elements belong ? (ii) What would be the nature of compound formed by a combination of elements B and F ? (iii) Which two of these elements could definitely be metals ? (iv) Which one of the eight elements is most likely to be found in gaseous state at room temperature ? (v) If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively, write the formula of the compound formed by the combination of C and G.

Write the names and symbols of two most reactive metals belonging to group I of the periodic table. Explain by drawing electronic structure how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known ? State any four physical properties of such compounds. Or What is meant by refining of a metals ? Name the most widely used method of refining impure metals produced by various reduction processes. Describe with the help of a labelled diagram how this method may be used for refining of copper.