Question

When a substance ' $A$ ' reacts with water, it produces a combustible gas ' $B$ ' and a solution of substance ' $C$ ' in water. while another substance ' $D$ ' reacts with solution of ' $C$ ' to produce the same gas $B$ on warming while ' $D$ ' can produce gas ' $B$ ' on reaction with dilute $H _{2} SO _{4}$ at room temperature. ' $A$ ' imparts a deep golden yellow colour to a smokeless flame on Bunsen burner. Identify 'A', $' B$ ', ' $C$ ' and ' $D$ ' respectively are

• A. $K, H_2, KOH, Al$
• B. $Na, H_2, NaOH, Zn$
• C. $CaC_2, C_2H_2, Ca(OH)_2, Fe$
• D. $Ca, H_2, Ca(OH)_2, Sn$

Answer 1

Answer: (B)

$Na, H_2, NaOH, Zn$

Answer 2

$\underset{A}{2Na} + 2H_2O \rightarrow \underset{B}{H_2} + \underset{C}{2NaOH}$ $\underset{D}{Zn} + \underset{C}{2NaOH} \xrightarrow{\Delta} Na_2ZnO_2 + \underset{B}{H_2}$ $\underset{D}{Zn} + H_2SO_4 \xrightarrow{\Delta} ZnSO_4 + \underset{B}{H_2}$ With Bunsen burner, $Na$ gives golden yellow flame, $K$ gives pink violet flame whereas $Ca$ gives brick red colour.