To check the principle of multiple proportions, a series of pure binary compounds $\left(\mathrm{P}_{\mathrm{m}} \mathrm{Q}_{\mathrm{n}}\right)$ were analyzed and their composition is tabulated below. The correct option(s) is(are) | Compound | Weight % of P | Weight % of Q | | --- | --- | --- | | 1 | 50 | 50 | | 2 | 44.4 | 55.6 | | 3 | 40 | 60 |

(B) If empirical formula of compound 3 is $\mathrm{P}_{3} \mathrm{Q}_{2}$ and atomic weight of element P is 20, then the atomic weight of Q is 45.; (C) If empirical formula of compound 2 is PQ, then the empirical formula of the compound 1 is $\mathrm{P}_{5} \mathrm{Q}_{4}$.

(A) If empirical formula of compound 3 is $\mathrm{P}_{3} \mathrm{Q}_{4}$, then the empirical formula of compound 2 is $\mathrm{P}_{3} \mathrm{Q}_{5}$.

(D) If atomic weight of P and Q are 70 and 35 , respectively, then the empirical formula of compound 1 is $\mathrm{P}_{2} \mathrm{Q}$.

JEE Advanced · 2022 · 28 Aug 2022 · Paper 2 · Some Basic Concepts of Chemistry

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To check the principle of multiple proportions, a series of pure binary compounds

(P_{m} Q_{n})

were analyzed and their composition is tabulated below. The correct option(s) is(are)

Compound	Weight % of P	Weight % of Q
1	50	50
2	44.4	55.6
3	40	60

(A)If empirical formula of compound 3 is $P_{3} Q_{4}$ , then the empirical formula of compound 2 is $P_{3} Q_{5}$ .
(B)If empirical formula of compound 3 is $P_{3} Q_{2}$ and atomic weight of element P is 20, then the atomic weight of Q is 45.✓ Correct
(C)If empirical formula of compound 2 is PQ, then the empirical formula of the compound 1 is $P_{5} Q_{4}$ .✓ Correct
(D)If atomic weight of P and Q are 70 and 35 , respectively, then the empirical formula of compound 1 is $P_{2} Q$ .

Answer: (B), (C)

Solution

For option (A): If compound 3 is

P_{3} Q_{4}

, then

\frac{40}{M _{P}} : \frac{60}{M _{Q}} = 3 : 4

, giving

9 M_{P} = 8 M_{Q}

. For compound 2:

\frac{44.4}{M _{P}} : \frac{55.6}{M _{Q}} = 9 : 10

, so the empirical formula is

P_{9} Q_{10}

, not

P_{3} Q_{5}

. Incorrect.

For option (B): If compound 3 is

P_{3} Q_{2}

, then

\frac{40}{M _{P}} : \frac{60}{M _{Q}} = 3 : 2

, giving

9 M_{P} = 4 M_{Q}

. If

M_{P} = 20

, then

M_{Q} = 45

. Correct.

For option (C): If compound 2 is PQ, then

\frac{M _{P}}{M _{Q}} = \frac{44.4}{55.6}

. For compound 1:

\frac{50}{M _{P}} : \frac{50}{M _{Q}} = M_{Q} : M_{P} = 55.6 : 44.4 \approx 5 : 4

, so empirical formula is

P_{5} Q_{4}

. Correct.

For option (D): With

M_{P} = 70

and

M_{Q} = 35

, for compound 1:

\frac{50}{70} : \frac{50}{35} = 1 : 2

, so empirical formula is

PQ_{2}

, not

P_{2} Q

. Incorrect.

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JEE Advanced · 2022 · 28 Aug 2022 · Paper 2 · Some Basic Concepts of Chemistry

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