Carbon and its Compounds: questions with answers

A triple bond has three shared electron pairs. Each pair is two electrons, so six electrons are shared.

Each oxygen atom needs two more electrons to complete its octet. The two atoms share two electron pairs, forming a double bond, so each reaches a stable outer shell of eight electrons.

Diamond and graphite are allotropes of carbon, but their carbon atoms are bonded in different networks. In diamond each carbon atom bonds to four others in a rigid structure, giving hardness. In graphite each carbon bonds to three others in layers, leaving free electrons that let it conduct electricity.

Catenation is carbon's ability to bond with itself into chains, branches and rings. Forming four bonds is tetravalency, a different property.

The functional group of a carbon compound decides its characteristic chemical reactions, not just its name or spelling.

Members of a homologous series share a functional group and general formula. Successive members differ by CH2, not CH3 or H2, and they are not identical in formula. Ethane (C2H6) and propane (C3H8) differ by CH2.

A saturated hydrocarbon has only single bonds between its carbon atoms. Ethane has one C-C single bond, so it is saturated. It has nothing to do with hydrogen gas.

A double bond is one bond in which the same two atoms share two electron pairs. It is not two separate single bonds.

Hot concentrated sulphuric acid removes water from ethanol at about 443 K to form ethene. It acts as a dehydrating agent.

Ethanol and methanol are different alcohols. Methanol is highly toxic and can cause blindness or death even in small amounts, while ethanol does not have this effect at ordinary drinking levels. This is why industrial ethanol is denatured with poisonous additives, to keep it from being drunk.

Ethane burns completely with enough oxygen, forming carbon dioxide and water. Too little air causes incomplete combustion, which can produce carbon monoxide and soot.

Hydrogen adds across the carbon-carbon double bonds of the unsaturated oil, with nickel as catalyst, turning it into a more saturated fat.

An alcohol and a carboxylic acid react in the presence of an acid catalyst, with warming, to form a sweet-smelling ester.

Rubbing or shaking helps detach oily dirt from fabric and disperse it into micelles formed by soap, so the dirt can be rinsed away.

Hard water contains calcium and magnesium ions. Detergents remain effective because their calcium and magnesium salts stay soluble, unlike soap, which forms an insoluble scum with these ions.