How do ortho and para hydrogen differ from each other?

$A$ body is projected from the earth at an angle of $30^{\circ}$ with the horizontal with some initial velocity. If its range is $20 \ m$,the maximum height reached by it is (in meters):

The hydride ion $H^-$ is a stronger base than the hydroxide ion $OH^-$. If sodium hydride $(NaH)$ is dissolved in water,which of the following reactions will occur?

If $3 \sin x + 4 \cos x = 5$,then $6 \tan \frac{x}{2} - 9 \tan^2 \frac{x}{2}$ is equal to

Assign $A, B, C, D$ from the given type of reaction.
$P_4 + 6Cl_2 \xrightarrow{\Delta} 4PCl_3$

Which among the following is $NOT$ a true statement for enantiomers?