CBSE Class 10 Science 2011 Question Paper

Draw the structure for ethanoic acid molecule, $CH_3COOH$.

Give an example of a phenomenon where Tyndall effect can be observed.

What is meant by biological magnification ?

Give an example to illustrate that indiscriminate use of pesticides may result in the degradation of the environment.

How does the valency of elements vary (i) in going down a group, and (ii) in going from left to right in a period of the periodic table ?

In the modern periodic table, the element Calcium (atomic number = 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these elements has physical and chemical properties resembling those of Calcium and why ?

State any four characteristics of the image of an object formed by a plane mirror.

Draw a ray diagram to show the refraction of light through a glass prism. Mark on it (a) the incident ray, (b) the emergent ray and (c) the angle of deviation.

Explain with the help of a diagram, how we are able to observe the sunrise about two minutes before the sun gets above the horizon.

List any four reasons for vegetative propagation being practised in the growth of some type of plants.

Describe the role of fallopian tubes in the female reproductive system.

List any four disadvantages of using fossil fuels for the production of energy.

Give two examples each of the following : (i) Renewable sources of energy (ii) Non-renewable sources of energy

Write chemical equations for what happens when (i) sodium metal is added to ethanoic acid. (ii) solid sodium carbonate is added to ethanoic acid. (iii) ethanoic acid reacts with a dilute solution of sodium hydroxide.

The atomic number of an element is 16. Predict (i) the number of valence electrons in its atom (ii) its valency (iii) its group number (iv) whether it is a metal or a non-metal (v) the nature of oxide formed by it (vi) the formula of its chloride

An object is placed between infinity and the pole of a convex mirror. Draw a ray diagram and also state the position, the relative size and the nature of the image formed.

What is the principle of reversibility of light ? Show that the incident ray of light is parallel to the emergent ray of light when light falls obliquely on a side of a rectangular glass slab.

What eye defect is myopia ? Describe with a neat diagram how this defect of vision can be corrected by using a suitable lens.

What does HIV stand for ? Is AIDS an infectious disease ? List any four modes of spreading AIDS.

Describe any three ways in which individuals with a particular trait may increase in population.

State the evidence we have for the origin of life from inanimate matter.

What are fossils? What do they tell us about the process of evolution?

(a) State two properties of carbon which lead to a very large number of carbon compounds. (b) Why does micelle formation take place when soap is added to water ? Why are micelles not formed when soap is added to ethanol ? OR Explain isomerism. State any four characteristics of isomers. Draw the structures of possible isomers of butane, $C_4H_{10}$.

(a) What is meant by 'power of a lens' ? (b) State and define the S.I. unit of power of a lens. (c) A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with each other. Calculate the lens power of this combination. OR (a) Draw a ray diagram to show the formation of image of an object placed between infinity and the optical centre of a concave lens. (b) A concave lens of focal length 15 cm forms an image 10 cm from the lens. Calculate (i) the distance of the object from the lens (ii) the magnification for the image formed (iii) the nature of the image formed

With the help of suitable diagrams, explain the various steps of budding in Hydra. OR What is binary fission in organisms ? With the help of suitable diagrams, describe the mode of reproduction in Amoeba.

To find the focal length of a concave mirror, Sita should choose which one of the following set-ups ?

By using a convex lens, a student obtained a sharp image of his class-room window grill on a screen. In which direction should he move the lens to focus a distant tree instead of the grill ?

To determine the focal length of a convex lens by obtaining a sharp image of a distant object, the following steps were suggested which are not in proper sequence : I. Hold the lens between the object and the screen. II. Adjust the position of the lens to form a sharp image. III. Select a suitable distant object. IV. Measure the distance between the lens and the screen. The correct sequence of steps to determine the focal length of the lens is

In these diagrams, the angle of refraction $r$ has been correctly marked in which diagram ?

For a ray of light passing through a glass slab the lateral displacement was correctly measured as

Iron nails were dipped in an aqueous solution of copper sulphate. After about 30 minutes, it was observed that the colour of the solution changed from

A cleaned aluminium foil was placed in an aqueous solution of zinc sulphate. When the aluminium foil was taken out of the zinc sulphate solution after 15 minutes, its surface was found to be coated with a silvery grey deposit. From the above observation it can be concluded that

Vapours of acetic acid smell

Acetic acid reacts with solid sodium hydrogen carbonate

A student added acetic acid to test tubes I, II, III and IV containing the labelled substances (I: $NaOH$, II: $NaCl$, III: $NaHCO_3$, IV: $Ca(OH)_2$) and then brought a burning splinter near the mouth of each test tube. The splinter would be extinguished when brought near the mouth of test tube

The shape of yeast cell is

The steps involved in observing a slide under a microscope are given below. They are not in proper sequence. I. Focus the object under high power of the microscope. II. Place the slide on the stage of the microscope. III. Arrange the mirror to reflect maximum light to the slide. IV. Focus the object under low power of the microscope. The proper sequence of steps is

The given figures illustrate binary fission in Amoeba in improper order. The correct order is

During the course of an experiment, 'to determine the percentage of water absorbed by raisins', raisins are weighed

The colour of raisins as used in the experiment, 'to determine the percentage of water absorbed by raisins' was

Following are the steps involved in the experiment 'to determine the percentage of water absorbed by raisins'. They are not in proper sequence. I. Soak the raisins in fresh water. II. Weigh dry raisins. III. Weigh soaked raisins. IV. Wipe out soaked raisins. The correct sequence of steps is