The amount of phosphorus present in $1.375 \mathrm{g}$ of ${\mathrm{PCl}}_3$ is

(Atomic weight of $\mathrm{P}=31$, $\mathrm{Cl}=35.5$)

A mixture contains $5.4 \mathrm{g}$ of $\mathrm{Al}$, $1.2 \mathrm{g}$ of $\mathrm{Mg}$ and $4.6 \mathrm{g}$ of ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$. The ratio of their moles is

(Atomic weights of $\mathrm{Al}=27 \mathrm{u}, \mathrm{Mg}=24 \mathrm{u}, \mathrm{C}=12 \mathrm{u}, \mathrm{O}=16 \mathrm{u}, \mathrm{H}=1 \mathrm{u}$)

Which of the following samples will have the same volume under similar conditions of temperature and pressure?

$\mathrm{a}.$ $64 \mathrm{g} {\mathrm{SO}}_2$

$\mathrm{b}.$ $4 \mathrm{g} \mathrm{He}$

$\mathrm{c}.$ $16 \mathrm{g} {\mathrm{O}}_2$

$\mathrm{d}.$ $6.023\times {10}^{23}$ molecules of ${\mathrm{N}}_2$.

The number of atoms in $3.2 \mathrm{g}$ of oxygen gas is

In which of the following pairs do $1 \mathrm{g}$ of each have an equal number of molecules?

Given that the abundance of isotopes ${}^{54}\mathrm{Fe}$, ${}^{56}\mathrm{Fe}$  and ${}^{57}\mathrm{Fe}$ in nature are $5\%, 90\%$ and $5\%$, respectively. The atomic mass of $\mathrm{Fe}$ is

A wedding ring presented to a bride contains $788 \mathrm{mg}$ of gold and the rest is diamond. If the weight of the ring is $1 \mathrm{gram}$, the bride receives 

(Atomic weight of $\mathrm{Au}=197$, $\mathrm{C}=12$)