The isoelectronic species among the following are:$I){\rm{CH}}_3^ + ;{\rm{II)NH}}_2^ + ;{\rm{III)NH}}_4^ + ;{\rm{IV)N}}{{\rm{H}}_3}$

What is the mass percent of carbon in $C{O_2}$

What is the mass of one mole of carbon dioxide (CO2)?

A gaseous mixture contains oxygen and nitrogen in the ratio of $1:4$ by weight. Therefore, the ratio of their number of molecules is:

In which case the number of molecules of water maximum

Which of the following contains the maximum number of water molecules?

Which of the following has the largest number of atoms?

The number of molecules present in 1 mL of gas or vapour at STP is:

If Avogadro's number were redefined as $6.022 imes 10^{26} \, mol^{-1}$, which of the following would be directly affected?

If Avogadro number, $N_A$, is changed from $6.022 imes 10^{23} \, mol^{-1}$ to $6.022 imes 10^{20} \, mol^{-1}$, this would change:

Number of molecules in 1 ml of ${O_2}$ at NTP