Download App

9. Hydricarbon — Chemistry STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 ScienceChemistry9. Hydricarbon1 Mark
MCQ
The decreasing order of boiling points is
  • ✓
    $n-$ Pentane > iso-Pentane > neo-Pentane
  • B
    iso-Pentane > $ n-$ Pentane > neo-Pentane
  • C
    neo-Pentane > iso-Pentane >$ n-$ Pentane
  • D
    $n-$ Pentane > neo-Pentane > iso-Pentane
✓

Answer

Correct option: A.
$n-$ Pentane > iso-Pentane > neo-Pentane
a
As the boiling point of an alkane depends on the surface area of a molecule, higher the surface is, higher the boiling point of alkane. The branched-chain isomer of an alkane has a lower surface area than that of its straight-chain isomer, so the branched-chain isomer of an alkane has a lower boiling point than its straight-chain isomer.

So, higher the branches, lower is the boiling point.

So, the order of boiling point of isomeric pentanes is $n -$ pentane $\,>\,$ iso $-$ pentane $\,>\,$ neo $-$ pentane.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 9. Hydricarbon→9. Hydricarbon — all question types→Chemistry STD 11 Science question papers→Rajasthan Board STD 11 Science question papers→Rajasthan Board question paper generator→

Similar questions

Which one of the following orders presents the correct sequence of the increasing basic nature of the given oxides ?
→
$Ce - 58$ is a member of
→
Assign $A, B, C, D$ from given type of reaction. $C{u^{2 + }}\left( {aq.} \right) + 2{I^ - } \longrightarrow CuI \downarrow  + \frac{1}{2}{I_2}$
→
The correct order in which the $O -O$ bond length increases in the following is
→
$Be's$ $4^{th}$ electron will have four quantum numbers

            $n$                  $l$                 $m$                 $s$

→
Second ionization potential of $Li, Be$ and $B$ is in the order
→
In a reversible reaction at $300\, K\, K_c > K_p$ and $\Delta H \Rightarrow  + 40\, Kcal$.  The product will be obtained in more amount on
→
The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front, substance $A$ and substance $B$ from the base line are $3.25\,cm .2 .08$ $cm$ and $1.05\,cm$. respectively. The ratio of $R_{f}$ values of $A$ to $B$ is$.........$
→
Which one of the following is not an alcohol?
→
Which one of the following molecules has a coordinate bond
→