In which of the following pairs of compounds is the ratio of $C$,$H$,and $O$ the same?

$A$ hydrocarbon contains $10.5 \,g$ of carbon and $1 \,g$ of hydrogen. If $2.4 \,g$ of this hydrocarbon occupies a volume of $1 \,L$ at $1 \,atm$ pressure and $127 \,^{\circ}C$ temperature,what is the molecular formula of the hydrocarbon?

An ornamental of gold having $75\%$ of gold,it is of .............. carat.

At $STP$,$2.8 \, L$ of a gaseous substance weighs $5.5 \, g$. If the compound contains $N$ and $O$ atoms,its molecular formula will be ..............

An organic compound has $C = 60\%$,$H = 13.3\%$ and $O = 26.7\%$. Its empirical formula will be

$A$ substance contains $38.8\% \, C$,$16\% \, H$,and $45.2\% \, N$. What is the empirical formula of the substance?