Q. A certain amount of a metal whose equivalent mass is 28 displaces 0.7 L of $H_{2}$ at STP from an acid. Hence, mass of the element is
A) 1.75 g
B) 0.875 g
C) 3.50 g
D) 7.00 g
Explanation
(a)
Mass of hydrogen $= \frac{0.7}{22.4} \times 2 = \frac{14}{224}g = 0.0625g$
$\because 0.0625\ g$ of hydrogen is displaced by $x$ g metal.
$\therefore$ 1g of hydrogen is displaced by $= \frac{x}{0.0625}g$ of metal
$\Longrightarrow \ \frac{x}{0.0625} = 28$
Eq. mass of metal, $x = 28 \times 0.0625 = 1.75g$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.