The species having a bond order different from that in $CO$ is

Match the following:
| Column $I$ | Column $II$ |
| :--- | :--- |
| $A$. Hooke's law | $1$. Tangential strain |
| $B$. Shearing strain | $2$. Temporary loss of elastic property |
| $C$. Bulk strain | $3$. Elastic limit |
| $D$. Elastic fatigue | $4$. $3$ times the linear strain |

An electron moves with speed $2 \times 10^5 \ m/s$ along the positive $x$-direction in the presence of a magnetic induction $\vec{B} = \hat{i} + 4\hat{j} - 3\hat{k}$ (in $Tesla$). The magnitude of the force experienced by the electron in Newtons is (charge on the electron = $1.6 \times 10^{-19} \ C$).

$A$ body is projected from the ground at an angle of $\tan ^{-1}(\sqrt{7})$ with the horizontal. At half of the maximum height, the speed of the body is '$n$' times the speed of projection. The value of '$n$' is

The random variable $X$ takes the values $1, 2, 3, \ldots, m$. If $P(X=n) = \frac{1}{m}$ for each $n$,then the variance of $X$ is

$A$ beam of light of wavelength $600\, nm$ from a distant source falls on a single slit $1\, mm$ wide and the resulting diffraction pattern is observed on a screen $2\, m$ away. The distance between the first dark fringes on either side of the central bright fringe is