Question

Which is used to produce smoke screens?
(A) Calcium phosphide
(B) Zinc sulphate
(C) Sodium carbonate
(D) Zinc phosphide

Answer 1

Hint: An inorganic compound which is responsible for producing smoke screens. And its trade name is Photophor for the incendiary use or Polytanol for the use as rodenticide. We will also describe the process of the production of smoke screens by chemical equations.

Complete answer:
Calcium phosphide is used to produce smoke screens.
A smoke screen is a dense cloud of fake smoke used to hide military areas or operations from an enemy. Calcium phosphide is responsible for its production:
\[C{a_3}P2 + 6{H_2}O \to 3Ca{(OH)_2} + 2P{H_3}\]
Phosphene $(P{H_3})$ so formed spontaneously catches fire to give ${P_2}{O_5}$ :
\[2P{H_3} + 4{O_2} \to {P_2}{O_5} + 3{H_2}O\]
${P_2}{O_5}$ forms a white dense smoke screen.
Calcium phosphide (CP) is the inorganic compound with the formula $C{a_3}{P_2}$ . It's one of several calcium phosphides, and it's defined as a salt-like substance made up of \[C{a^{2 + }}\] and ${P^{3 - }}$ .
Other, more exotic calcium phosphides have the formula \[CaP,{\text{ }}Ca{P_3},{\text{ }}C{a_2}{P_2},{\text{ }}and{\text{ }}C{a_5}{P_8}\] .
Hence, the correct option is (A) Calcium phosphide.

Note:
Smoke screens are employed in combat to disguise and camouflage soldiers. Smoke screens can also be made with very small titanium oxide particles scattered in the air. Because titanium oxide is so dense, the smoke screen quickly dissipates as a dazzling white curtain.