$0.24\mathrm{g}$ sample of a compound of oxygen and boron was found by analysis to contain $0.144\mathrm{g}$ of oxygen and $0.096\mathrm{g}$ of boron. Calculate the percentage composition of the compound by weight. 

In a non-stoichiometric sample of cuprous sulphide, with the composition ${\mathrm{Cu}}_{1.8}\mathrm{S},$ cupric ions are also present in the lattice. What mole percent of ${\mathrm{Cu}}^{2+}$ is present in the copper content of the crystal?

When $0.15 \mathrm{g}$ of an organic compound was analyzed using Carius method for estimation of bromine, $0.2397 \mathrm{g}$ of $\mathrm{AgBr}$ was obtained. The percentage of bromine in the organic compound is _________.(Nearest integer)

[Atomic mass : Silver $=108,$ Bromine $=80$]

$116 \mathrm{g}$ of a substance upon dissociation reaction, yields $7.5 \mathrm{g}$ of hydrogen, $60 \mathrm{g}$ of oxygen and $48.5 \mathrm{g}$ of carbon. Given that the atomic masses of $\mathrm{H},\mathrm{O}$ and $\mathrm{C}$ are $1,16$ and $12$, respectively. The data agrees with how many formulae of the following?

A. ${\mathrm{CH}}_3\mathrm{COOH}$

B. $\mathrm{HCHO}$

C. ${\mathrm{CH}}_3{\mathrm{OOCH}}_3$

D. ${\mathrm{CH}}_3\mathrm{CHO}$