The oxidation number of $Pt$ in $[Pt(C_2H_4)Cl_3]^-$ is

When two species of different genealogy come to resemble each other as a result of adaptation,the phenomenon is termed as

If $\left(1+\frac{3}{1}\right)\left(1+\frac{5}{4}\right)\left(1+\frac{7}{9}\right) \ldots\left(1+\frac{2n+1}{n^2}\right)=121$,then $n=$

$A$ proton, a deuteron (nucleus of ${ }_1 H^2$) and an $\alpha$-particle with the same kinetic energy enter a region of uniform magnetic field moving at right angles to the field. The ratio of the radii of their circular paths is:

$A$ spring of spring constant $5 \times 10^3 \, N/m$ is stretched initially by $5 \, cm$ from the unstretched position. Then the work required to stretch it further by another $5 \, cm$ is .............. $N-m$.

If $\sin 6 \theta + \sin 4 \theta + \sin 2 \theta = 0$, then the general value of $\theta$ is