ECAT MCQs

Hydrocarbons are the simplest organic compounds.
They include alkanes, alkenes, alkynes, and aromatic compounds.

The pi bond prevents free rotation.
Each double-bond carbon must have two different substituents for geometric isomerism.

Alkanes are saturated because they contain the maximum number of hydrogens.
Their general acyclic formula is CnH2n+2.

Addition reactions reduce unsaturation.
Alkenes commonly undergo electrophilic addition.

Alkenes are unsaturated hydrocarbons.
Their double bond contains one sigma and one pi bond.

Substitution preserves much of the carbon skeleton.
Halogenation of alkanes is an example.

Alkynes are unsaturated hydrocarbons.
The triple bond contains one sigma and two pi bonds.

Elimination often removes H and another group from adjacent atoms.
It commonly forms an alkene.

Each carbon in an alkane forms four bonds.
An open-chain saturated hydrocarbon follows CnH2n+2.

Complete combustion gives carbon dioxide and water.
Limited oxygen may produce carbon monoxide or soot.

One double bond reduces hydrogen count by two relative to an alkane.
Thus the formula is CnH2n.

Hydrogenation converts an unsaturated bond toward saturation.
A metal catalyst is commonly used.