In the half-wave rectifier circuit shown,which one of the following waveforms is true for $V_{CD}$,the output across $C$ and $D$?

If the straight lines $2x + 3y - 1 = 0$,$x + 2y - 1 = 0$ and $ax + by - 1 = 0$ form a triangle with the orthocentre at the origin,then $(a, b) =$

Two charges $+3.2 \times 10^{-19} \, C$ and $-3.2 \times 10^{-19} \, C$ kept $2.4 \, \mathring{A}$ apart form a dipole. If it is placed in a uniform electric field of intensity $4 \times 10^5 \, V/m$,what will be its potential energy in stable equilibrium?

$\int_0^2 \frac{2x-2}{2x-x^2} dx$ is equal to

Rearrange the following ($I$ to $IV$) in the order of increasing masses:
$I$. $0.5$ mole of $O_3$
$II$. $0.5$ g-atoms of oxygen
$III$. $3.011 \times 10^{23}$ molecules of $O_2$
$IV$. $5.6$ $L$ of $CO_2$ at $STP$

If $Q$ denotes the set of all rational numbers and $f\left(\frac{p}{q}\right)=\sqrt{p^2-q^2}$ for any $\frac{p}{q} \in Q$,then observe the following statements.
$I$. $f\left(\frac{p}{q}\right)$ is real for each $\frac{p}{q} \in Q$
$II$. $f\left(\frac{p}{q}\right)$ is a complex number for each $\frac{p}{q} \in Q$.
Which of the following is correct?