NCERT MCQ Solutions for Class 10 Science Chapter 4 Carbon and its Compounds

Carbon has four valence electrons and needs four more to complete its octet. It forms four covalent bonds with other atoms in order to achieve a stable electron configuration which explains its valency of 4.

Methane is the simplest saturated hydrocarbon with a single bond between all atoms. Saturated hydrocarbons are alkanes that contain only single bonds and do not have double or triple bonds.

Covalent compounds are held together by weak intermolecular forces which require less energy to break. As a result they have low melting and boiling points and are usually poor conductors of electricity.

Graphite has a layered structure where layers can slide over each other due to weak forces between them. This slippery nature makes it suitable as a solid lubricant in machines and engines.

Esters react with bases in hydrolysis reactions to form alcohols and carboxylic acids. This reaction forms the basis of soap-making known as saponification which is widely used in industries.

Ethyne has a triple bond between two carbon atoms which is characteristic of alkynes. Triple bonds result in linear molecular geometry and increased reactivity compared to single or double bonds.

Alkanes are saturated hydrocarbons with only single covalent bonds. The general formula CₙH₂ₙ₊₂ indicates that each carbon atom forms four bonds by combining with sufficient hydrogen atoms.

When ethanol reacts with sodium metal hydrogen gas is liberated. This reaction forms sodium ethoxide and is also used to confirm the presence of alcohols in a compound.

Diamond has a tetrahedral structure where each carbon atom is bonded to four others with strong covalent bonds. This makes diamond extremely hard and useful for cutting tools and abrasives.

In hydrogenation hydrogen gas is added to unsaturated fats in the presence of a catalyst to convert double bonds to single bonds turning them into saturated fats used in food products.

Esters are responsible for the sweet fruity smells found in perfumes and food flavorings. They are formed by the reaction of alcohols with carboxylic acids under specific conditions.

Unlike soaps detergents do not form insoluble scum with the calcium and magnesium ions in hard water. This makes them more effective for cleaning in regions where water is hard.

Methanol (CH₃OH) contains a hydroxyl group (–OH) which classifies it as an alcohol. Alcohols are organic compounds with one or more hydroxyl groups attached to a carbon atom.

A homologous series is a group of organic compounds with a similar structure and functional group where each successive member differs by a –CH₂ unit in molecular structure.

Alcohols react with sodium to release hydrogen gas and form alkoxides. This test is a quick way to identify the presence of alcohol functional groups in organic compounds.

The hydroxyl group (–OH) is the defining functional group of alcohols. It influences the compound’s properties such as solubility in water and its ability to undergo oxidation.

Soap forms an insoluble precipitate or scum when it reacts with calcium and magnesium ions present in hard water. This reduces its effectiveness in cleaning clothes and utensils.

Acetic acid (CH₃COOH) contains a –COOH functional group which is characteristic of carboxylic acids. It is responsible for the sour taste and acidic nature of vinegar.

Ethene (C₂H₄) is the simplest alkene containing two carbon atoms and one double bond. It is an important raw material in the production of plastics and other chemicals.

Alkenes contain double bonds and react with bromine in an addition reaction that results in the decolorization of the brown bromine water which serves as a test for unsaturation.