1.

In which of the following compounds the percentage of carbon atom is highest ?

Answer»

`CH_(3)-CH_(2)-CH_(3)`
`underset("OH")underset("|")(CH_(3)-CH-CH_(3))`
`C_(12)H_(22)O_(11)`
`CH_(3)COOH`

Solution :% C `=(100xx "wt. of carbon")/("molecular mass")`
(A) `CH_(3)CH_(2)CH_(3) -= C_(3)H_(8)`
`= 3 (C) + 8 (H)`
`= 3 (12) + 8 (1)`
`= 36 + 8`
`= 44 g* "mol"^(-1)` and36 g Carbon in it.
% C `= (100xx36)/(44) = 81.818 % C`......(A)
`underset("OH")underset("|")(CH_(3)+CH-CH_(3)-=C_(3)H_(8)O)`
`3(C) + 8(H) + 1(16)`
`= 36+8 + 16`
`= 60 g "mol"^(-1)` and 36 g C in it.
`% C = (100xx36)/(60) = 60% C `.........(B)
(C) `C_(12)H_(22)O_(11)`
`= 12(C) + 22(H) +11(O)`
`= 12(12)+22(1) + 11(16)`
`= 144+22+176`
`= 342g* "mol"^(-1)` and144 g C in it.
`% C = (144xx100)/(342) = 42.105% C`......(C)
(D) `CH_(3)COOH -= C_(2)H_(4)O_(2)`
`=2(C)+4(H) +2(O)`
`=2(12)+4(1)+2(16)`
`= 24+4+32`
`= 60 g "mol"^(-1)`and `24 g` C in it.
`%C = (24)/(60) XX 100 = 40% C `.......(D)


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