Question

A compound $\left(X\right)$ imports a golden yellow flame and shows the following reactions:
(i) Zinc powder when boiled with a concentrated aqueous solution of (X) dissolves and hydrogen is evolved.

(ii) When an aqueous solution of $\left(X\right)$ is added to an aqueous solution of stannous chloride, a white precipitate is obtained first which dissolves in excess of a solution of $\left(X\right)$.

The molecular weight of $\left(X\right)$ is:

• A. 40
• B. 58.5
• C. 85
• D. 35

Answer 1

The correct option is A 40

The compound $\left(X\right)$ is $NaOH$.
Compound $\left(X\right)$ imports a golden yellow flame and shows the following reactions:
(i) Zinc powder when boiled with a concentrated aqueous solution of (X) dissolves and hydrogen is evolved
$Zn+NaOH\to N{a}_{2}Zn{O}_2+H_2$
(ii) When an aqueous solution of $\left(X\right)$ is added to an aqueous solution of stannous chloride, a white precipitate is obtained first which dissolves in excess of solution of $\left(X\right)$ .The molecular weight of $X$ is 40 g/mol.
$2NaOH+SnC{l}_2\to \underset{whiteppt.}{Sn(OH{)}_2\downarrow }+2NaCl$
$Sn(OH{)}_2+2NaOH\to N{a}_{2}Sn{O}_2+2H_{2}O$