Alkane

Select the incorrect statement regarding alkanes.

• It is otherwise known as Paraffin

• It is an acyclic saturated hydrocarbon

• In alkanes, C-C bonds are single

• Alkanes have the general formula CnH2n

Answer explanation

Because the general formula of alkanes is CnH2n+2

Identify the simplest alkane.

• Methane

• Methene

• Ethane

• Ethene

Answer explanation

Because Methane is the first member of Alkanes

Select the minimum number of carbon atoms, a molecule must possess so as to be regarded as a higher alkane.

• 15

• 16

• 17

• 18

Answer explanation

A molecule with more than 17 carbon atoms are regarded as higher alkanes such as waxes and solids.

Identify the incorrect statement.

• Alkanes with repeated –CH2– units constitute a homologus series

• They are very reactive

• They have very less biological activity

• Petroleum and natural gas are the main sources of alkanes

Answer explanation

Because alkanes are slow to react because they contain covalent bonds

Which among the following is not an alkane isomer with 6 carbon atoms?

• Hexane

• 2,3-dimethylbutane

• 2,2-dimethylbutane

• Neopentane

Answer explanation

Because it has 5 carbons, not 6

The other name for branched chain alkanes is

• Paraffins

• Isoparaffins

• Neoparaffins

• Naphthenes

Answer explanation

Alkanes are called paraffins because they have a little affinity towards a general reagent. In other words, alkanes are inert substances. They undergo reactions under drastic conditions.

Select the incorrect statement regarding the boiling points of alkanes.

• Boiling point increases with stronger Vander Waal’s forces

• Surface area is the only factor which determines the boiling point of alkane

• Boiling point of straight chain alkanes is greater than that of branched chain alkanes

• The boiling point of cycloalkanes is always higher than that of linear alkanes

Answer explanation

Because there are other factors such as molecular weight, The number of carbon atoms and the number of branches.

Choose the correct statement.

• Alkanes have poor conductivity

• They form hydrogen bonds

• They have good solubility in non polar solvents than polar solvents

• Alkanes have less density than that of water

Answer explanation

Because alkanes float on the surface of water like oils

Liquified petroleum gas is mainly composed of

• Methane and ethane

• Ethane and propane

• Propane and butane

• Butane and hexane

Answer explanation

Because LPG Liquefied Petroleum Gas composed of the hydrocarbons. It is mainly consisting of propane and butane.

An alkane with 6 carbon atoms will have how many hydrogen atoms?

• 11

• 12

• 13

• 14

Answer explanation

Because the general formula of alkanes is C_nH_2n+2

Then number of hydrogens is (2x6)+2 = 12+2=14