Two elements A and B which form 0.15 moles of $\mathrm{A}_{2} \mathrm{~B}$ and $\mathrm{AB}_{3}$ type compounds. If both $\mathrm{A}_{2} \mathrm{~B}$ and $\mathrm{AB}_{3}$ weigh equally, then the atomic weight of A is \_\_\_\_ times of atomic weight of B .

JEE Main · 2022 · 27 Jun 2022 · Shift 1 · Some Basic Concepts of Chemistry

Two elements A and B which form 0.15 moles of

A_{2} B

and

AB_{3}

type compounds. If both

A_{2} B

and

AB_{3}

weigh equally, then the atomic weight of A is
____ times of atomic weight of B .

Answer: 2

Given that equal masses of

A_{2} B

and

AB_{3}

are formed, their molar masses must be equal:

Molar mass of

A_{2} B

= Molar mass of

AB_{3}

2 A + B = A + 3 B

where A and B represent the atomic weights of elements A and B respectively.

Solving:

2 A - A = 3 B - B

A = 2 B

Therefore, the atomic weight of A is 2 times the atomic weight of B.

JEE Main · 2022 · 27 Jun 2022 · Shift 1 · Integer answer