Question

A silvery-white metal $X$ reacts with water at room temperature to produce a water-soluble compound $Y$ and a colourless gas $Z$. The reactions are highly exothermic and the $Z$ catches fire immediately during the reaction. The solution of $Y$ in the water on reacting with a stoichiometric amount of dilute solution of hydrochloric acid gives a solution of pH$=7.0$. The compounds $X,Y$ and $Z$ respectively are:

• A. $Al,Al(OH{)}_3$ and $H_2$
• B. $Ag,AgOH$ and $H_2$
• C. $K,KCl$ and $H_2$
• D. $Na,NaOH$ and $H_2$

Answer 1

Answer: (D)

$Na,NaOH$ and $H_2$

Here,

• $X$ is a silvery white metal. i.e. $X$ is $Na$.
• The water-soluble compound $Y$ is $NaOH$.
  
• The colourless gas produced is $H_2$.

• Reaction : $Na+H_{2}O\to NaOH+H_2$

• $NaOH+HCl\to NaCl+H_{2}O$