$10 \ g$ $NaHCO_{3(s)}$ sample is heated in open to constant weight,the residue is titrated against $0.1 \ M \ HCl$ in presence of phenolphthalein as an indicator,$500 \ mL$ of acid was required to reach end point hence $PERCENT$ purity of sample is $............... \%$.

In a $20\%$ aqueous solution of $H_2O_2$,the mole fraction of water is $.......$.

When metallic copper comes in contact with moisture,a green powdery/pasty coating can be seen over it. This is chemically known as

If $1 \ g$ of each of the following gases are taken at $STP$,which of the gases will occupy $(a)$ greatest volume and $(b)$ smallest volume? $CO, H_2O, CH_4, NO$

For the reaction: $N_{2(g)} + 3H_{2(g)} \rightarrow 2NH_{3(g)}$,$\Delta H = -24 \ \text{kcal}$ at $427 \ ^\circ\text{C}$ and $200 \ \text{atm}$. Calculate the magnitude of the internal energy change ($\Delta U$ in $\text{kcal}$),if $168 \ \text{g}$ of $N_2$ gas and $30 \ \text{g}$ of $H_2$ gas are allowed to react completely ($100\%$ reaction yield) to form $NH_3$ gas at $427 \ ^\circ\text{C}$ and $200 \ \text{atm}$.

When $800 \ mL$ of $0.5 \ M$ nitric acid is heated in a beaker,its volume is reduced to half and $11.5 \ g$ of nitric acid is evaporated. The molarity of the remaining nitric acid solution is $x \times 10^{-2} \ M$. (Nearest Integer) (Molar mass of nitric acid is $63 \ g \ mol^{-1}$)