Q. The substance used in smoke screen is
A) Sodium chloride
B) Sodium phosphate
C) Calcium fluoride
D) Calcium phosphide
Explanation
(d)
$Ca_{3}P_{2} + 6H_{2}O \rightarrow 3Ca(OH)\ _{2} + 2PH_{3}$
$PH_{3}$ contain $P_{2}H_{4}$ an as impurity which on burning gives $P_{2}O_{5}$ and white smoke
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.