Which of the following elements has the maximum first ionisation potential?

If $\sin ^{-1} x - \cos ^{-1} x = \frac{\pi}{6}$,then $x$ is equal to

If $\left|\begin{array}{cc}1-i & i \\ 1+2 i & -i\end{array}\right|=x+i y$,then $x$ is equal to

The number of values of $x$ in the interval $[0, 5\pi]$ satisfying the equation $3\sin^2x - 7\sin x + 2 = 0$ is

Carbohydrates,the most abundant biomolecules on Earth,are produced by:

$A$ parallel plate capacitor is charged to a potential difference of $100\ V$ and disconnected from the source of emf. $A$ slab of dielectric is then inserted between the plates. Which of the following three quantities change?
$(i)$ The potential difference
$(ii)$ The capacitance
$(iii)$ The charge on the plates