Question

The atomic mass number of zinc is 66 and its valency is 2. the mass of zinc liberated by 9.65 a of current in 10 sec will be

• A. 33 $\mu$g
• B. 33 mg
• C. 33 g
• D. 33 kg

Answer 1

Answer: (B)

33 mg

Given
The atomic mass number of zinc is $Z=66$.
The valency of Zinc is $v=2$.
The current is $I=9.65A$.
Time $t=10$ s.
The current is rate of flow of charge, hence if $q$ is the charge flowing in circuit then
$I=\frac{q}{t}$
$q=It=9.65\times 10=96.5C$
Now, the mass of zinc liberated by 96500 charge (i.e. 1F charge) is $\frac{Z}{v}=\frac{66}{2}=33g$.
Hence, the mass of zinc liberated by charge $q$ is
$m=\frac{33\times 96.5}{96500}=33mg$