Question

The molecular weight of oxide of an element is $44$. The equivalent weight of the element is $14$. The atomic weight of the element is

• A. $7$
• B. $14$
• C. $28$
• D. $56$

Answer 1

The correct option is B

$14$

Explanation for correct option:

(b) $14$

• Let the molecular formula of an oxide be ${\mathrm{M}}_2{\mathrm{O}}_{\mathrm{x}}$
• The given molecular weight is $44$.
• $$\begin{gathered} \mathrm{M}=\mathrm{atomic}\mathrm{weight} \\ \mathrm{E}=\mathrm{equivalent}\mathrm{weight} \\ \mathrm{x}=\mathrm{no}.\mathrm{of}\mathrm{atoms}\mathrm{of}\mathrm{O}\mathrm{in}{\mathrm{M}}_2{\mathrm{O}}_{\mathrm{x}} \end{gathered}$$
• $$\begin{gathered} 2\times \mathrm{M}+\mathrm{x}\times 16=44 \\ 2(\mathrm{E}\times \mathrm{x})+\mathrm{x}\times 16=44 \\ 2(14\times \mathrm{x})+16\mathrm{x}=44 \\ \therefore \mathrm{x}=1 \end{gathered}$$
• $\mathrm{Atomic}\mathrm{weight}=14\times 1=14$
• Hence this is the correct option.

Explanation for incorrect options:

(a) $7$

• The calculated atomic weight is $14$
• but this option states atomic weight to be $7$
• Hence this is the incorrect option.

(c) $28$

• The calculated atomic weight is $14$
• but this option states atomic weight to be $28$
• Hence this is the incorrect option.

(d) $56$

• The calculated atomic weight is $14$
• but this option states atomic weight to be $56$
• Hence this is the incorrect option.

So option (b) $14$is the correct answer.