$A$ compound has $50\%$ carbon,$50\%$ oxygen and its approximate molecular weight is $290$. Its molecular formula is

In the crystalline solid $MSO_{4} \cdot nH_{2}O$ of molar mass $250 \ g \ mol^{-1}$, the percentage of anhydrous salt is $64$ by weight. The value of $n$ is

$A$ compound contains $2.8\%$ $Fe$ by mass. If the compound contains a single $Fe$ atom in its one molecule,then the molar mass $(g/mol)$ of the compound is $(Fe = 56\, amu)$.

$A$ welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives $3.38 \ g$ of carbon dioxide,$0.690 \ g$ of water and no other products. $A$ volume of $10.0 \ L$ of this welding gas (measured at $STP$) is found to weigh $11.6 \ g$. Calculate: $(i)$ Empirical formula,$(ii)$ Molar mass of the gas,$(iii)$ Molecular formula.

In each molecule of carbon tetrachloride,the mass percent of carbon and chlorine respectively are

If two compounds have the same empirical formula but different molecular formulae,they must have: