Okay so your answer for n is
Molecular mass of nitrogen, N2 = 2*14 = 28
molecular mass of hydrogen, H2=2*1 = 2
Molecules of both elements contain 2 atoms, so the ratio of molecules is the same as the ratio of atoms.
From the molecular masses above,
ratio of number of molecules = ratio of molecular masses, therefore
7g N2 : x g H2 = 28:2
cross multiply:
x=7*2/28=0.5 g of Hydrogen has the same number of atoms as 7 g of nitrogen (at room temperatures)
Answer : The volume of pure diamond is 
Explanation : Given,
Density of pure carbon in diamond = 
Moles of pure diamond = 23.7 moles
Molar mass of carbon = 12 g/mol
First we have to calculate the mass of carbon or pure diamond.
Molar mass of carbon = 12 g/mol

Now we have to calculate the volume of carbon or pure diamond.
Formula used:

Now putting all the given values in this formula, we get:

Volume = 
As we know that:

So,
Volume = 
Volume = 
Therefore, the volume of pure diamond is 
H2SO4 is an acid
the chemical equation showing how H2SO4 is an acid according to the Arrhenius definition is as below
H2SO4 dissociate to give 2H^+ and SO4^2-
that is H2SO4 = 2H^+ + SO4^2-
According to Arrhenius an acid dissociate to give H^+ ions H2SO4 is an acid since it dissociate to give two hydrogen ions