Calculate the percent atom economy when a product of formula weight $$175 \mathrm{u}$$ is obtained in a chemical reaction using $$225 \mathrm{u}$$ formula weight reactant.

According to reaction,

$$\mathrm{Mg}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{MgCl}_2(a q)+\mathrm{H}_2(g) \uparrow .$$

Calculate the mass of $$\mathrm{Mg}$$ required to liberate $$4.48 \mathrm{~dm}^3 \mathrm{~H}_2$$ at STP?

(Molar mass of $$\mathrm{Mg}=24 \mathrm{~g} \mathrm{~mol}^{-1}$$)

What is the value of percent atom economy when an organic compound of formula weight $$75 \mathrm{~u}$$ is obtained from reactants having sum formula weight $$225 \mathrm{~u}$$ ?

Which from following substances consists of total 1 mole atoms in it? (Molar mass of $$\mathrm{NH}_3=17, \mathrm{H}_2 \mathrm{O}=18, \mathrm{~N}_2=28, \mathrm{CO}_2=44$$ )