A) NH_{3 }
_{molecular mass of }NH_{3 =(1\(\times atomic \space mass \space of \space N\)} ) +\((3\times\) atomic mass of H)
\(=(1\times14 u)+(3\times 1u)\)
=17 u
B) CH_{3 }COOH
molecular mass of CH_{3 }COOH =\((2\times atomic \space mass \space of \space C)\) + (2\(\times atomic \space mass \space of \space O\) ) +(4\(\times atomic \space mass \space of \space H\) )
=\((2\times 12u)+(2\times 16u)+(4\times 1u)\)
=60 u
C) C_{2}H_{5}OH
molecular mass of C_{2}H_{5}OH = \((2\times atomic \space mass \space of \space C)+(6\times atomic \space mass \space of \space H)+(1\times atomic \space mass \space of \space O)\)
=\((2\times 12u)+(6\times 1u)+(1\times 16u)\)
=46 u