Question

$Y$ (an element) is a substance which reacts with oxygen in the air vigorously to give compound $Z$. So, $Y$ is stored under water usually. $Z$ when dissolved in water gives a compound whose formula is:

• A. $H_2{YO}_2$
• B. $H_2{YO}_3$
• C. $H_3{YO}_4$
• D. $HY$

Answer 1

The correct option is C $H_3{YO}_4$

Answer is option $C.$

Phosphorus is highly reactive when exposed to air and stored under water.

$P$ reacts with oxygen to form phosphorus pentoxide.

$\underset{Y}{4P}+5O_2⟶\underset{Z}{2P_2{O}_5}$

Phosphorus pentoxide reacts with water to form $H_{3}P{O}_4$.

$P_2{O}_5+3H_{2}O⟶\underset{\text{phosphoric acid}}{2H_{3}P{O}_4}$

Formula is $H_{3}Y{O}_4$.