JEE Main 2015 — Chemistry Physical Chemistry

2015mcqmedium

In the following reaction:

$A+2B+3C\rightleftharpoons A{B}_{2}{C}_{3}$

$6.0g$ of $A$ , $6.0\times {10}^{23}$ atoms of $B$ and $0.036\mathrm{mol}$ of $C$ reacted and formed $4.8g$ of compound $A{B}_{2}{C}_{3}$ . If the atomic mass of $A$ and $C$ are $60$ and $80\mathrm{amu}$ , respectively. What is the atomic mass of $B$ in $\mathrm{amu}$ ? (Avogadro number $=6\times {10}^{23}$ )

Official previous-year question

Held on 11 Apr 2015 · Verified 6 Jul 2026.

Options

A
$40\mathrm{amu}$
B
$60\mathrm{amu}$
C
$70\mathrm{amu}$
D
$50\mathrm{amu}$

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Solution

$\begin{matrix} & \text{A} & + & 2 \text{B} & + & 3 \text{C} & \rightarrow & {\text{AB}}_{2} {\text{C}}_{3} \\ & 6 \text{g} & & 6 \times 1 {0}^{ 2 3 } \text{atoms} & & \text{0.036} moles & & \\ \text{Moles} & \frac{ 6 }{ 6 0 } & & \frac{ 6 \times 1 {0}^{ 2 3 } }{ 6 \times 1 {0}^{ 2 3 } } & & & & \\ & \text{0.1 mole} & & \text{1.0 mole} & & \text{0.036 moles} & & \end{matrix}$

$(\frac{0.1}{1} ,\frac{1.0}{2} ,\frac{0.036}{3};the least value is 0.012, i.e., C is \mathrm{the}\mathrm{li}miting \mathrm{re}agent)$

$0.036\mathrm{moles}$ of $C$ provides $0.012\mathrm{moles}$ of $A{B}_{2}{C}_{3}$ .

$0.012\mathrm{moles}$ of $A{B}_{2}{C}_{3}$ weighs $4.8 g$

$1\mathrm{mole}$ of ${\mathrm{AB}}_{2}{C}_{3}$ weighs $\frac{4.8}{0.012}=400g{\mathrm{mol}}^{-1}$

$400=60+2B+3\times 80$

$B=50 \mathrm{amu}$

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Solution

$(\frac{0.1}{1} ,\frac{1.0}{2} ,\frac{0.036}{3};the least value is 0.012, i.e., C is \mathrm{the}\mathrm{li}miting \mathrm{re}agent)$

$0.036\mathrm{moles}$ of $C$ provides $0.012\mathrm{moles}$ of $A{B}_{2}{C}_{3}$ .

$0.012\mathrm{moles}$ of $A{B}_{2}{C}_{3}$ weighs $4.8 g$

$1\mathrm{mole}$ of ${\mathrm{AB}}_{2}{C}_{3}$ weighs $\frac{4.8}{0.012}=400g{\mathrm{mol}}^{-1}$

$400=60+2B+3\times 80$

$B=50 \mathrm{amu}$

JEE Main 2015 — Chemistry Physical Chemistry

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JEE Main Physical Chemistry in other years

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JEE Main 2015 — Chemistry Physical Chemistry

Options

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Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry