Percentage of gold in $14$ carat gold is (in $\%$)

$925$ fine silver means an alloy of :

$A$ pure compound contains $2.4 \ g$ of $C$,$1.2 \times 10^{23}$ atoms of $H$,and $0.2 \ mol$ of oxygen atoms. Its empirical formula is

$A$ compound gave $80\%$ carbon and $20\%$ hydrogen on analysis. The compound is possibly

An organic compound on analysis gave the following results: $C = 54.5\%$,$O = 36.4\%$,$H = 9.1\%$. The empirical formula of the compound is:

$0.102 \ g$ of an organic compound $X$ was oxidised with fuming nitric acid. The resulting solution,after reaction with excess of aqueous $BaCl_2$,produced $0.233 \ g$ of $BaSO_4$ as a precipitate. Compound $X$ is likely to be: [Given: Atomic wt. of $Ba = 137$]