4. Carbon and its Compounds Science class 10 in English Medium ncert book solutions Chapter Review

Chapter Review:

• The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogencarbonates, coal and petroleum) and the atmosphere has 0.03% of carbon dioxide.
• Ionic compounds have high melting and boiling points and conduct electricity in solution or in the molten state.
• The atomic number of chlorine is 17.
• Such bonds which are formed by the sharing of an electron pair
  between two atoms are known as covalent bonds.
• Covalent bond molecules are seen to have strong bonds within the molecule, but intermolecular forces are small.
• Carbon has three allotropes (i) graphite (ii) diamond (iii) C-60
  Buckminsterfullerene.
• Diamond is the hardest substance known while graphite is smooth and slippery. Graphite is also a very good conductor of electricity.
• The formation of covalent bonds by the sharing of electrons in various elements and compounds.
• Compounds of carbon, which are linked by only single bonds between the carbon atoms are called saturated compounds.
• Compounds of carbon having double or triple bonds between their
  carbon atoms are called unsaturated compounds.
• The two characteristic features seen in carbon, that is, tetravalency and catenation.
• Compound of carbon and hydrogen has the formula C₂H_​4 and is called ethene.
• Compound of hydrogen and carbon has the formula C₂H₂ and is called ethyne.
• Such compounds with identical molecular formula but different structures are called structural isomers.
• All these carbon compounds which contain just carbon and hydrogen
  are called hydrocarbons.
• The saturated hydrocarbons are called alkanes.
• The unsaturated hydrocarbons which contain one or more double bonds are called alkenes.
• Those containing one or more triple bonds are called alkynes.
• Such a series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series.
• Carbon allotropic forms, burns in oxygen to give carbon dioxide
  along with the release of heat and light.
• Unsaturated hydrocarbons add hydrogen in the presence of catalysts
  such as palladium or nickel to give saturated hydrocarbons.
• VegeTable oils generally have long unsaturated carbon chains while
  animal fats have saturated carbon chains.
• Ethanol is a liquid at room temperature.is commonly called alcohol and is the active ingredient of all alcoholic drinks. In addition, because it is a good solvent, it is also used in medicines such as tincture iodine, cough syrups, and many tonics.
• Ethanol produced for industrial use, it is made unfit for drinking by adding poisonous substances like methanol to it. Dyes are also added to colour the alcohol blue so that it can beidentified easily. This is called denatured alcohol.
• Ethanoic acid is commonly called acetic acid and belongs to a group of acids called carboxylic acids. 5-8% solution of acetic acid in water is called vinegar.
• Esters are sweet-smelling substances. These are used in making perfumes and as flavouring agents.
• Soaps are molecules in which the two ends have differing properties, one is hydrophilic,that is, it dissolves in water, while the other end is hydrophobic, that is, it dissolves in hydrocarbons.
• Detergents are generally ammonium or sulphonate salts of long chain
  carboxylic acids. The charged ends of these compounds do not form
  insoluble precipitates with the calcium and magnesium ions in hard
  water.