A steady current of 1.5 A flows through a copper voltameter for 10...

If $m$ is the mass of a substance deposited or liberated at an electrode during electrolysis when a charge $q$ passes through electrolyte, then according to Faraday's first law of electrolysis, or $$\begin{aligned} & m \propto q \\ & m=z q \end{aligned}$$ where $z$ is a constant of proportionality and is called electrochemical equivalent (ECE) of the the substance. If an electric current $I$ flows through the electrolyte, then $\therefore$$\begin{aligned} q & =I t \\ m & =z i t \end{aligned}$$$Here,$$\begin{aligned} i=1.5 \mathrm{~A}, t & =10 \mathrm{~min}=10 \times 60 \mathrm{~s}, \\ z & =30 \times 10^{-5} \mathrm{gC}^{-1} \end{aligned}$$Hence, mass of copper deposited on the electrode$$\begin{aligned} m & =30 \times 10^{-5} \times 1.5 \times 10 \times 60 \\ & =27 \times 10^{-2}=0.27 \mathrm{~g} \end{aligned}$$