Which gland is concerned with salt equilibrium in the body?

Charges of $+\frac{10}{3} \times 10^{-9} \text{ C}$ are placed at each of the four corners of a square of side $8 \text{ cm}$. The potential at the intersection of the diagonals is:

Four resistors $A, B, C$ and $D$ form a Wheatstone bridge as shown in the figure. The bridge is balanced when $C = 100 \Omega$. If $A$ and $B$ are interchanged,the bridge balances for $C = 121 \Omega$. The value of $D$ is (in $\Omega$)

If $x=a\left\{\cos \theta+\log \tan \left(\frac{\theta}{2}\right)\right\}$ and $y=a \sin \theta$,then $\frac{d y}{d x}$ is equal to

Haploids are more suitable for mutation studies than diploids. This is because

If $z=\log (\tan x+\tan y)$, then $(\sin 2x) \frac{\partial z}{\partial x}+(\sin 2y) \frac{\partial z}{\partial y}$ is equal to