$5 \mathrm{g} \mathrm{of} \mathrm{NaOH}$ was dissolved in deionized water to prepare a $450 \mathrm{mL}$ stock solution. What volume (in mL) of this solution would be required to prepare $500 \mathrm{mL}$ of $0.1 \mathrm{M}$ solution ? Given : Molar Mass of $\mathrm{Na}, \mathrm{O} \mathrm{and} \mathrm{H} \mathrm{is} 23, 16 \mathrm{and} 1 \mathrm{g} {\mathrm{mol}}^{–1}$ respectively

Uracil is base present in $\mathrm{RNA}$  with the following structure. $\% \mathrm{of} \mathrm{N}$ in uracil is _______.

The number of units, which are used to express concentration of solutions from the following is _________.

(Mass percent, Mole, Mole fraction, Molarity, ppm, Molality.)

In sulphur estimation. $0.471 \mathrm{g}$ of an organic compound gave $1.4439 \mathrm{g}$ of barium sulphate. The percentage of sulphur in the compound is _______(Nearest Integer)

(Given: Atomic mass Ba: $137\mathrm{u}:\mathrm{S}:32\mathrm{u},\mathrm{O}:16\mathrm{u}$ )

The volume of $\mathrm{HCl}$, containing $73\mathrm{g} {\mathrm{L}}^{-1}$, required to completely neutralise $\mathrm{NaOH}$ obtained by reacting $0.69 \mathrm{g}$ of metallic sodium with water, is _____ $\mathrm{mL}$. (Nearest Integer)

(Given : molar Masses of $\mathrm{Na},\mathrm{Cl},\mathrm{O},\mathrm{H}$ are $23,35.5,16$ and $1\mathrm{g} {\mathrm{mol}}^{-1}$ respectively)