Which of the following groups of mineral elements is present in higher amounts in living organisms?

If $\cot ^{-1}(\sqrt{\cos \alpha})-\tan ^{-1}(\sqrt{\cos \alpha})=x$,then the value of $\sin x$ is

If $\sqrt{x} + \frac{1}{\sqrt{x}} = 2\cos \theta$,then ${x^6} + {x^{-6}} = $

How many litres of oxygen (at $STP$) are required for complete combustion of $39 \text{ g}$ of liquid benzene? (Atomic weights: $C=12, O=16, H=1$)

$A$ circular coil of area $200 ~cm^2$ and $50$ turns is rotating about its vertical diameter with an angular speed of $40 ~rad/s$ in a uniform horizontal magnetic field of magnitude $2 \times 10^{-2} ~T$. The maximum emf induced in the coil is (in $~V$)

What is the pressure on a swimmer $20 \, m$ below the surface of water in $atm$?