Who among the following scientists made the statement "Chemical change can produce electricity"?

$A$ storage cell is charged by $5\, A$ $D.C.$ for $18\, hours$. Its strength after charging will be .............. $AH$.

What is called the internal resistance of a cell?

When two identical batteries of internal resistance $1 \Omega$ each are connected in series across a resistor $R$,the rate of heat produced in $R$ is $J_1$. When the same batteries are connected in parallel across $R$,the rate is $J_2$. If $J_1 = 2.25 J_2$,then the value of $R$ in $\Omega$ is

$A$ battery consists of $n$ rows of cells connected in parallel,with each row containing $m$ cells in series. The maximum current is obtained through an external resistance of $3 \, \Omega$. If the total number of cells is $24$ and the internal resistance of each cell is $0.5 \, \Omega$,find the values of $m$ and $n$.

The potential difference between the terminals of a cell is $20 \ V$ when a current of $2 \ A$ flows through the circuit. When the direction of current in the circuit is reversed,the potential difference between the terminals of the cell is $30 \ V$. The internal resistance of the cell is (in $Omega$)