Which property among the following is the same for both hydrogen and deuterium molecules?

If the point $P(1,3)$ undergoes the following transformations successively:
$(i)$ Reflection with respect to the line $y=x$.
(ii) Translation through $3$ units along the positive direction of the $X$-axis.
(iii) Rotation through an angle of $\frac{\pi}{6}$ about the origin in the clockwise direction.
Then,the final position of the point $P$ is

Differentiate the function with respect to $x$: $\sec (\tan (\sqrt{x}))$

What is the order of esterification of alcohols?

If the slope of one of the pair of lines represented by $2x^2 + 3xy + Ky^2 = 0$ is $2$,then the angle between the pair of lines is

The coefficient of $x^n$ in $\frac{1-2x}{e^x}$ is: