The number of unit cells present in $39 \ g$ of potassium if it crystallizes as body-centered cubic $(BCC)$ is ($N = \text{Avogadro number}$,$\text{At. wt. of potassium} = 39$).

The Cartesian form of the polar equation $\theta = \tan^{-1} 2$ is

Two persons $A$ and $B$ are located in the $X-Y$ plane at the points $(0,0)$ and $(0,10)$ respectively. (The distances are measured in $MKS$ units). At time $t=0$,they start moving simultaneously with velocities $\overrightarrow{v}_A = 2\hat{j} \text{ m/s}$ and $\overrightarrow{v}_B = 2\hat{i} \text{ m/s}$ respectively. The time after which $A$ and $B$ are at their closest distance is

Two bar magnets $A$ and $B$ are placed one over the other and are allowed to vibrate in a vibration magnetometer. They make $20$ oscillations per minute when the similar poles of $A$ and $B$ are on the same side,while they make $15$ oscillations per minute when their opposite poles lie on the same side. If $M_A$ and $M_B$ are the magnetic moments of $A$ and $B$ and if $M_A > M_B$,the ratio of $M_A$ and $M_B$ is

Cry $II$ Ab and Cry $I$ Ab produce toxins that control:

Let $A$ and $B$ be two sets,then: