Question

How many grams of $Cu{\left(N{O}_3\right)}_{2}1$ is needed to get $1$ gram of copper?
(atomic mass $Cu=63.5,N=14,O=16$ )

• A. 1.00
• B. 2.00
• C. 1.95
• D. 2.95

Answer 1

Answer: (D)

In $Cu{\left(N{O}_3\right)}_2$
Given, atomic mass of
$Cu=63.5\times \frac{1}{5}=63.5$
$N=14\times 2=28$
$O=16\times 6=96$
Total mass $=63.5+28+96=187.5g$
$\because 63.5$ of copper will get by
$=187.5g$ of $Cu{\left(N{O}_3\right)}_2$
$\therefore 1g$ of copper will get by
$=\frac{187}{63.5}=2.95g$