In compound $X$,all the bond angles are exactly ${109^o}28'$,$X$ is

Select the correct statement from the following.

Which of the following compounds when heated with $CO$ at $150^{\circ} C$ and $500 \ atm$ pressure in the presence of $BF_3$ forms ethyl propionate?

$A$ convex mirror of focal length $f$ forms an image which is $1/n$ times the object. The distance of the object from the mirror is

$A$ ball falls from a height $h$ and rebounds after striking the floor. The coefficient of restitution is $e$. The total distance covered before it comes to rest is

The maximum number of sub-levels,orbitals and electrons in $N$ shell of an atom are respectively