(i) NH4NO3 => 14 + 1 x 4 + 14 + 16 x 3 = 80 u

(ii) H2SO4 => 2 x 1 +1 x 32 + 4 x 16 = 98 u

(iii) Na2CO3 => 2 x Na + 1 x C + 3 x O

= 2 x 23 + 1 x 12 + 3 x 16 = 106 u

(iv) NaOH => 1 x Na + 1 x O + 1 x H = 1 x 23 + 1 x 16 + 1 x 1 = 40 u

(v) HNO3 => 1 x Na + 1 x H + 3 x O = 1 x 1 + 1 x 14 + 3 x 16 = 63 u

(vi) Al2(SO4)3 => 27 x 2 + 32 x 3 + 16 x 12 = 342 u