When $1\,g$ of hydrogen $(e.c.e. = 1.044 \times 10^{-8}\,kg/C)$ forms water,$34\,kcal$ of heat is liberated. The minimum voltage required to decompose water is ............. $V$.

Two resistances $R_1$ and $R_2$ when connected in series and parallel with a $120\, V$ line,the power consumed is $25\, W$ and $100\, W$ respectively. The ratio of the power consumed by $R_1$ to that consumed by $R_2$ is:

In an electroplating experiment,a current of $4 \ A$ is passed for $2 \ min$ to deposit a mass $m$ of silver. If a current of $6 \ A$ is passed for $40 \ s$,the mass of silver deposited is:

In the circuit shown here,the readings of the ammeter and voltmeter are

The expression for thermo $e.m.f.$ in a thermocouple is given by the relation $E = 40\theta - \frac{\theta^2}{20}$,where $\theta$ is the temperature difference of two junctions. For this,the neutral temperature will be ................... $^oC$.

If a battery of voltage $V$ is connected across terminals $I$ of the black box shown in the figure,an ideal voltmeter connected to terminals $II$ gives a reading of $V/2$. While if the battery is connected to terminals $II$,a voltmeter across terminals $I$ reads $V$. The black box may contain: