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

Q: 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

The correct option is **D** (Group 16 and Period 3 / (A), (B) and (C)). ### Explanation: 1. **First Part:** Non-metals generally form acidic oxides when dissolved in water (as stated in the NCERT text: *"Most non-metals produce acidic oxides when dissolve in water"*). Sulphur ($\text{S}$) is a non-metal with atomic number 16, which places it in **Group 16 and Period 3** of the modern periodic table. It burns in air to form sulphur dioxide ($\text{SO}_2$), an acidic oxide. 2. **OR Part:** Element 'X' with 13 protons is Aluminium ($\text{Al}$). - **Statement (A) is correct:** Aluminium forms aluminium oxide ($\text{Al}_2\text{O}_3$), which is an amphoteric oxide because it reacts with both acids and bases to produce salt and water. - **Statement (B) is correct:** Aluminium has an electronic configuration of $2, 8, 3$, giving it a valency of $3$. - **Statement (C) is correct:** Since the valency of Aluminium is $3$ and Chlorine is $1$, it forms a chloride with the chemical formula $\text{XCl}_3$ (i.e., $\text{AlCl}_3$). Therefore, all statements (A), (B), and (C) are correct, matching option **D**.

Metals and Non-metals

Chemical Properties of Metals and Non-metals

Options

(0)Group 1 and Period 3 / only (A)

(1)Group 2 and Period 3 / only (B)

(2)Group 13 and Period 3 / (A) and (C)

(3)Group 16 and Period 3 / (A), (B) and (C)

Official Answer

The correct option is D (Group 16 and Period 3 / (A), (B) and (C)).

Explanation:

First Part: Non-metals generally form acidic oxides when dissolved in water (as stated in the NCERT text: "Most non-metals produce acidic oxides when dissolve in water"). Sulphur ( $\text{S}$ ) is a non-metal with atomic number 16, which places it in Group 16 and Period 3 of the modern periodic table. It burns in air to form sulphur dioxide ( $\text{SO}_2$ ), an acidic oxide.
OR Part: Element 'X' with 13 protons is Aluminium ( $\text{Al}$ ).

Statement (A) is correct: Aluminium forms aluminium oxide ( $\text{Al}_2\text{O}_3$ ), which is an amphoteric oxide because it reacts with both acids and bases to produce salt and water.
Statement (B) is correct: Aluminium has an electronic configuration of $2, 8, 3$ , giving it a valency of $3$ .
Statement (C) is correct: Since the valency of Aluminium is $3$ and Chlorine is $1$ , it forms a chloride with the chemical formula $\text{XCl}_3$ (i.e., $\text{AlCl}_3$ ).

Therefore, all statements (A), (B), and (C) are correct, matching option D.

acidic oxidenon-metalGroup 16amphoteric oxidealuminium oxidevalencychloride

Marking Scheme

1Identify the correct option D with valid reasoning for both the main question and the OR alternative.

Hint

Recall that non-metals form acidic oxides, while the element with atomic number 13 is Aluminium, which forms an amphoteric oxide and has a valency of 3.

Quick Oral Answer

An amphoteric oxide is one that reacts with both acids and bases to form salt and water. Examples from our syllabus are aluminium oxide ( $\text{Al}_2\text{O}_3$ ) and zinc oxide ( $\text{ZnO}$ ).

Analysis & Explanation

This question tests the understanding of the chemical properties of oxides and the periodic classification of elements.

Acidic Oxides: Non-metals form acidic oxides. Sulphur (Group 16, Period 3) forms $\text{SO}_2$ , which reacts with water to form sulphurous acid ( $\text{H}_2\text{SO}_3$ ).
Amphoteric Oxides: Aluminium (atomic number 13) forms $\text{Al}_2\text{O}_3$ . The NCERT text explicitly highlights that aluminium oxide and zinc oxide show both acidic and basic behaviour, reacting with both acids (like $\text{HCl}$ ) and bases (like $\text{NaOH}$ ) to form salts (like $\text{AlCl}_3$ and $\text{NaAlO}_2$ ) and water. This confirms statement (A). Its valency of 3 leads to the chloride formula $\text{AlCl}_3$ , confirming statements (B) and (C).

Distractor Analysis:

Option A: Group 1 elements form basic oxides (e.g., $\text{Na}_2\text{O}$ ), not acidic oxides. Statement (A) alone is incomplete for the OR part.
Option B: Group 2 elements form basic oxides (e.g., $\text{MgO}$ ). Statement (B) alone is incomplete.
Option C: Group 13 elements form amphoteric/basic oxides, not purely acidic. Statements (A) and (C) are correct but omit statement (B), which is also correct.

Common Mistakes

1Confusing amphoteric oxides with acidic or basic oxides only.
2Forgetting that aluminium has 3 valence electrons and thus exhibits a valency of 3, forming $\text{AlCl}_3$ .

Interesting Facts

Aluminium oxide is highly stable and forms a natural protective layer on the surface of aluminium metal, preventing it from further corrosion. This property is exploited industrially in the process of anodising.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2020?

This question carries 1 mark in the CBSE Class 10 Science 2020 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Metals and Non-metals" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Chemical Properties of Metals and Non-metals" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2020 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2020 paper.