Which of the following is incorrect with respect to $Chondrichthyes$?

In which of the following arrangements is the order $NOT$ according to the property indicated against it?

The conversion of $O$-acylated phenol to $C$-acylated phenol in the presence of $AlCl_3$ is an example of which type of organic reaction?

The coordinates of the point $P$ on the curve $x=a(\theta+\sin \theta), y=a(1-\cos \theta)$,where the tangent is inclined at an angle $\frac{\pi}{4}$ to the $x$-axis,are

The number of atoms/molecules contained in one face-centred cubic $(FCC)$ unit cell of a monoatomic substance is

If $\bar{a}=\frac{1}{\sqrt{10}}(3 \hat{i}+\hat{k})$ and $\bar{b}=\frac{1}{7}(2 \hat{i}+3 \hat{j}-6 \hat{k})$,then the value of $(2 \bar{a}-\bar{b}) \cdot ((\bar{a} \times \bar{b}) \times (\bar{a}+2 \bar{b})) = $