Calculate the molecular mass of the following compounds:
$(i)$ $NH_{4}NO_{3}$
$(ii)$ $H_{2}SO_{4}$
$(iii)$ $Na_{2}CO_{3}$
$(iv)$ $NaOH$
$(v)$ $HNO_{3}$
$(vi)$ $Al_{2}(SO_{4})_{3}$

(N/A) $(i)$ $NH_{4}NO_{3} = 14 + (1 \times 4) + 14 + (16 \times 3) = 14 + 4 + 14 + 48 = 80 \ u$
$(ii)$ $H_{2}SO_{4} = (2 \times 1) + 32 + (4 \times 16) = 2 + 32 + 64 = 98 \ u$
$(iii)$ $Na_{2}CO_{3} = (2 \times 23) + 12 + (3 \times 16) = 46 + 12 + 48 = 106 \ u$
$(iv)$ $NaOH = 23 + 16 + 1 = 40 \ u$
$(v)$ $HNO_{3} = 1 + 14 + (3 \times 16) = 1 + 14 + 48 = 63 \ u$
$(vi)$ $Al_{2}(SO_{4})_{3} = (2 \times 27) + 3 \times [32 + (4 \times 16)] = 54 + 3 \times [32 + 64] = 54 + 3 \times 96 = 54 + 288 = 342 \ u$