The  balanced chemical reaction is given as:

Now, convert  into litres.
 into litres.

So, 
Density is equal to the ratio of mass to the volume.

where, M = mass and V= volume 
Substitute the value of density and volume in formula to get the value of mass.



Now, number of moles of  gas=
 gas=
= 
According to the reaction, 2 moles of sodium azide gives 3 moles of nitrogen gas.
Now, in 24.00 moles of nitrogen gas produced from=  of nitrogen gas, moles of sodium azide.
 of nitrogen gas, moles of sodium azide.
number of moles of sodium azide  = 
Mass of sodium azide in g  =   .
.
= 
= 
Thus, mass of sodium azide which is required to produce  of nitrogen gas  =
 of nitrogen gas  = 