Arrange the following in the order of increasing mass (atomic mass: $O = 16, Cu = 63, N = 14$)
$I.$ one atom of oxygen
$II.$ one atom of nitrogen
$III.$ $1 \times 10^{-10}$ mole of oxygen
$IV.$ $1 \times 10^{-10}$ mole of copper

What is the percentage of lead in a lead pencil (in $\%$)?

$10 \, mL$ of concentrated $H_2SO_4$ $(18 \, M)$ is diluted to $1 \, L$. The approximate strength of the dilute acid is.....$N$

Blue vitriol is

An athlete is given $100 \ g$ of glucose $(C_6H_{12}O_6)$ for energy. This is equivalent to $1800 \ kJ$ of energy. The $50 \ \%$ of this energy gained is utilized by the athlete for sports activities at the event. In order to avoid storage of energy,the weight of extra water he would need to perspire is $......... \ g$ (Nearest integer).
Assume that there is no other way of consuming stored energy. Given: The enthalpy of evaporation of water is $45 \ kJ \ mol^{-1}$.
Molar mass of $C, H$ and $O$ are $12, 1$ and $16 \ g \ mol^{-1}$.

$16 \ g$ each of $H_2$,$He$,and $O_2$ are present in a container exerting $10 \ atm$ pressure at $T \ (K)$. The pressure in $atm$ exerted by $16 \ g$ each of $He$ and $O_2$ in the second container of same volume and temperature is