The number of unpaired electrons in an $O_2$ molecule is

A capacitor $C$ is first charged fully with potential difference of $V_{0}$ and disconnected from the battery. The charged capacitor is connected across an inductor having inductance $L$. In time $t$, $25 \%$ of the initial energy in the capacitor is transferred to the inductor. The value of $t$ is

The radius of a circular plate is increasing at the rate of $0.01 \text{ cm/s}$ when the radius is $12 \text{ cm}$. Then,the rate at which the area increases,is

The potential difference between $A$ and $B$ in the figure is ................. $V$.

Which scientific term is used for a convenient category for the study of organisms like fish and mammals?

$A$ clock pendulum made of invar has a period of $0.5 \, s$ at $20^{\circ} C$. If the clock is used in a climate where the temperature averages to $30^{\circ} C$, how much time does the clock lose in each oscillation? (For invar, $\alpha = 9 \times 10^{-7} /{ }^{\circ} C$, $g = \text{constant}$)