Which of the following is a dihydric alcohol?

The Henry's law constant for the solubility of $N_2$ gas in water at $298 \ K$ is $1.0 \times 10^5 \ atm$. The mole fraction of $N_2$ in air is $0.8$. The number of moles of $N_2$ from air dissolved in $10 \ moles$ of water at $298 \ K$ and $5 \ atm$ pressure will be:

The height of the cone of maximum volume inscribed in a sphere of radius $R$ is

$A$ ladder is leaned against a smooth wall and it is allowed to slip on a frictionless floor. Which figure represents the track of its centre of mass?

The $IUPAC$ name of $(CH_3)_2CH-CH_2-CH_2Br$ is