Arrange the following in decreasing order of their boiling points.
(A) n-butane
(B) 2-methylbutane
(C) n-pentane
(D) 2,2-dimethylpropane

Options

A. `AgtBgtCgtD`
B. `BgtCgtDgtA`
C. `DgtCgtBgtA`
D. `CgtBgtDgtA`

Answer

D

Explanation

As the number of carbon atom increases, boiling point increases. Boiling point decreases with branching.
2,2-Dimethyl propane,- `underset(("b.pt=282.5"))(H_(3)C-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-CH_(3))`
n-pentane- `underset((b.pt=309.1K))(H_(3)C-CH_(2)-CH_(2)-CH_(2)-CH_(3))`
2-methyl butane- `underset((b.pt=301K))(H_(3)C-H_(2)C-Hunderset(CH_(3))underset(|)(C)-CH_(3))`
n-butane- `underset(("4 carbon atoms with no braching"))underset((b.pt=273K))(H_(3)C-H_(2)C-CH_(2)-CH_(3))`