The number of geometrical isomers for octahedral $[Co(NH_3)_2Cl_4]^-$,square planar $[AuCl_2Br_2]^-$ and $[Pt(en)Cl_2]$ are

In which of the following reactions does $HNO_3$ $NOT$ act as an oxidizing agent?

In a bicycle,the radius of the rear wheel is twice the radius of the front wheel. If $r_F$ and $r_r$ are the radii,and $v_F$ and $v_r$ are the velocities of the highest points of the front and rear wheels respectively,then:

If $A = \{2, 4, 5\}$ and $B = \{7, 8, 9\}$,then $n(A \times B)$ is equal to:

The number of possible enantiomeric pairs that can be produced on monochlorination of $2$-methylbutane is

If $u=\sin ^{-1}\left(\frac{x}{y}\right)+\tan ^{-1}\left(\frac{y}{x}\right)$,then the value of $x \frac{\partial u}{\partial x}+y \frac{\partial u}{\partial y}$ is