Atomic and Molecular Mass

How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of  $\text{PbO}$ and 3.2 g of  $\mathrm{HCl}$? Molar mass of $\mathrm{PbO}$ is equal to 223 g/mol.

Specific volume of a cylindrical virus particle whose radius and length are $7 \mathrm{\AA }$ and $10 \mathrm{\AA }$ respectively, is  $6.02\times {10}^{-2}\mathrm{cc}/\mathrm{g}$. If  ${\mathrm{N}}_{\mathrm{A}}=6.02\times {10}^{23}$, find the molecular weight of the virus:

The common isotopes of carbon are ${}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$. The average mass of carbon is $12.01115 \mathrm{amu}$. What is the abundance of the ${}^{13}\mathrm{C}$ isotope?

Which atom was originally used as a reference element for defining the atomic masses of other atoms.

The relative atomic mass of nitrogen assuming oxygen as the reference element is

Which element is used as a reference element in the present system of atomic masses?

A gas mixture contains $50\raisebox{1ex}{$ o$}\!\left/ \!\raisebox{-1ex}{$o$}\right.$ helium and $50 \raisebox{1ex}{$o$}\!\left/ \!\raisebox{-1ex}{$o$}\right.$ methane by volume. What is the percentage by weight of methane in the mixture?

A gas mixture contains $50\%$ helium and $50\%$ methane by volume. What is the percentage by weight of methane in the mixture?

An element X has the following isotopic composition:
${}^{200}\mathrm{X}:90\raisebox{1ex}{$ \mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,  ${}^{199}\mathrm{X}:8.0 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,   ${}^{202}\mathrm{X}:2 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$
The weighted average atomic mass of the naturally occurring element X is close to

The gram atomic mass of zinc is:

Which is the correct gram molecular mass of ammonia?

A gas mixture contains $50\raisebox{1ex}{$ o$}\!\left/ \!\raisebox{-1ex}{$o$}\right.$ helium and $50 \raisebox{1ex}{$o$}\!\left/ \!\raisebox{-1ex}{$o$}\right.$ methane by volume. What is the percentage by weight of methane in the mixture?

An element X has the following isotopic composition:
${}^{200}\mathrm{X}:90\raisebox{1ex}{$ \mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,  ${}^{199}\mathrm{X}:8.0 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,   ${}^{202}\mathrm{X}:2 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$
The weighted average atomic mass of the naturally occurring element X is close to

Average atomic mass of $\mathrm{Mg}$ is approximately equal to. (Given that percentage abudance of ${{12}^{\mathrm{Mg}}}^{24}$, ${{12}^{\mathrm{Mg}}}^{25}$ and ${{12}^{\mathrm{Mg}}}^{26}$ are $79\%, 10\% \mathrm{and} 11\%$, respectively)

Suppose 1/4^th part by weight of an atom of He⁴ isotope is taken as 1u rather than the present convention, then what will be the expected atomic weight of Al on this scale? (Atomic weight of Al, C and He on C¹² - scale are 27, 12 and 4.003 respectively)

An organic compound has molecular weight $90$, and has the empirical formula ${\mathrm{CH}}_2\mathrm{O}$. The molecular formula of the compound is: 

A mixture contain oxygen and nitrogen gas in a close container. In the above gaseous mixture if SO₂ gas is introduced then which of the following will be correct?