Question

Which is used to produce smoke screen?

• A. Calcium phosphide
• B. Zinc sulphate
• C. Sodium carbonate
• D. Zinc phosphide

Answer 1

The correct option is A Calcium phosphide

Smoke screen is a mass of dense artificial smoke used to conceal military areas or operations from an enemy.It is produced by calcium phosphide

$C{a}_3{P}_2+6H_{2}O\to 3Ca(OH{)}_2+2P{H}_3$

Phosphene ($P{H}_3$) so formed spontaneously catches fire to give $P_2{O}_5$

$2P{H}_3+4O_2\to P_2{O}_5+3H_{2}O$.

$P_2{O}_5$ forms a white dense smoke screen.

Hence option $A$ is correct.