Question

How many grams of $Cu \left( NO _{3}\right)_{2} 1$ 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 $Cu \left( NO _{3}\right)_{2}$
Given, atomic mass of
$C u=63.5 \times \frac{1}{5}=63.5$
$N=14 \times 2=28 $
$O=16 \times 6=96$
Total mass $=63.5+28+96=187.5\, g$
$\because 63.5$ of copper will get by
$=187.5 \,g$ of $Cu \left( NO _{3}\right)_{2}$
$\therefore 1 \,g$ of copper will get by
$=\frac{187}{63.5}=2.95\, g$