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.

Assertion (A): As stated in Section 3.4.5, 'The metals high up in the reactivity series are very reactive. They cannot be obtained from their compounds by heating with carbon... because these metals have more affinity for oxygen than carbon.' Hence Assertion (A) is true.

Reason (R): Section 3.4.4 confirms that displacement reactions (using highly reactive metals like sodium, calcium, aluminium as reducing agents, e.g. the thermit reaction $\text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow 2\text{Fe}(l) + \text{Al}_2\text{O}_3(s) + \text{Heat}$) can indeed be used to obtain metals. Hence Reason (R) is also true.

However, R does not explain why metals high in the reactivity series specifically cannot be reduced by carbon. The actual reason (given in the text) is that these metals have a greater affinity for oxygen than carbon does, so carbon cannot displace them from their oxides — this is unrelated to the general statement that displacement reactions can be used to obtain metals (which applies to obtaining less reactive metals using more reactive ones as reducing agents, e.g. using Al to reduce $\text{Fe}_2\text{O}_3$, not to extracting the top-of-series metals themselves). Metals at the very top (K, Na, Ca, Mg, Al) are instead obtained by electrolytic reduction (Section 3.4.5), not simple displacement.

Therefore both statements are factually true, but R is not the correct explanation of A — option (B).

• (A) Incorrect — R does not correctly explain A.
• (C) Incorrect — R is true, not false; displacement reactions are indeed valid methods described in the chapter.
• (D) Incorrect — A is true, not false; the chapter explicitly states this fact.