CBSE Solutions for Class 10 English

જવાબ : (i) homologous
(ii) C_nH_2n+2
(iii) saturated
(iv) hydrocarbons
(v) substitution
(vi) methane

જવાબ : Ethene

જવાબ : Spurious liquor

જવાબ : Dehydration

જવાબ : Hydrogenation

જવાબ : Pyrolysis

જવાબ : Acetic acid

જવાબ : Formalin

જવાબ : Ethene / Ethyne

જવાબ : Ammoniacal cuprous chloride

જવાબ : Calcium carbide

જવાબ : Alcohol

જવાબ : Carboxylic acid

જવાબ : Vinegar

જવાબ : Molybdenum oxide

જવાબ : Methane

જવાબ : Oxidizing agents are the substances which give oxygen to another substances or which remove hydrogen from a substance.
For example, acidic K₂Cr₂O₇ is an oxidizing agent that converts (oxidizes) ethanol into ethanoic acid.

જવાબ : Carbon and its compounds are used as fuels for most of the applications because they burn in air releasing a lot of heat energy.

જવાબ : The conversion of ethanol into ethanoic acid is called an oxidation reaction because oxygen is added to it during this conversion

જવાબ :

જવાબ :

જવાબ : Addition reactions take place only in unsaturated hydrocarbons. So addition reaction take place only in C₃H₆ and C₂H₂.

જવાબ : The addition of hydrogen to an unsaturated hydrocarbon to obtain a saturated hydro-carbon is called hydrogenation. The process of hydrogenation takes place in the presence of nickel (Ni) or palladium (Pd) metals as catalyst.

Application : The process of hydrogenation has an important industrial application. It is used to prepare vegetable ghee (or vanaspati ghee) from vegetable oils.

જવાબ : Red litmus will turn blue because soap is alkaline in nature. Blue litmus remains blue in soap solution.

જવાબ : Hard water contains salts of calcium and magnesium. Calcium and magnesium on reacting with soap form insoluble precipitate called scum. The scum formation lessens the cleansing property of soaps in hard water.

જવાબ : Carbon and its compounds give a large amount of heat per unit weight and are therefore, used as fuels for most applications.

જવાબ : Micelle formation takes place when soap is added to water because the hydrocarbon chains of soap molecules are hydrophobic (water repelling) which are insoluble in water, but the ionic ends of soap molecules are hydrophilic (water attracting) and hence soluble in water.
Such micelle formation will not be possible in other solvents like ethanol in which sodium salt of fatty acids do not dissolve.

જવાબ : Homologous series : A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by -CH₂ group.

જવાબ : It is necessary to agitate to get clean clothes because the soap micelles which entrap oily or greasy particles on the surface of dirty cloth have to be removed from its surface. When the cloth wetted in soap solution is agitated or beaten, the micelles containing oily or greasy dirt get removed from the surface of dirty cloth and go into water and the dirty cloth gets cleaned.

જવાબ : No, because detergents can lather well even in hard water. They do not form insoluble calcium or magnesium salts (scum). On reacting with the calcium ions and magnesium ions present in the hard water.

જવાબ : The hydrocarbon belongs to alkene family. It is unsaturated in nature.

જવાબ : Candle flame is generally yellow due to the presence of unburnt carbon particles. When light falls on these particles, they scatter yellow colour. This shows that the combustion of hydrocarbons present in wax or candle is not complete.

જવાબ : Aldehydic group

જવાબ : The family is of aldehydes also called alkanals.

જવાબ : They have the common functional group.

જવાબ : This is due to the self linking property of carbon known as catenation.

જવાબ : Carbon is tetravalent in its compounds.

જવાબ : Carbon and hydrogen are the essential constituents of all organic compounds. However, carbon tetrachloride (CCl₄) is an exception.

જવાબ : It is a class of chemical reactions in which the net result is addition of hydrogen (H₂) to unsaturated organic compounds such as alkenes, alkynes, etc. Hydrogenation is widely applied to the processing of vegetable oils and fats. Complete hydrogenation converts unsaturated fatty acids to saturated ones.

જવાબ : Soap is the salt of a strong base (NaOH) and a weak acid (carboxylic acid), so a solution of soap in water is basic in nature. Being basic, a soap solution turns red litmus paper blue.

જવાબ : The functional group (—COOH) is known as carboxyl group.

જવાબ :

જવાબ : They have the same functional group (—OH) known as alcoholic group.

જવાબ : The compound is ethanol with formula C₂H₅OH.

જવાબ : The formula of butene is C₄H₈.

જવાબ : C₃H₄ has triple bond with the formula CH₃C ≡ CH

જવાબ : C₃H₆ and C₄H₈ belong to the same homologous series which is alkenes with general formula C_nH_2n.

જવાબ : CH₃COCH₃ : Propanone, Acetone
C₂H₅COOH : Propanoic acid, Propionic acid.

જવાબ : Soap helps in forming a stable emulsion between oil drops carrying dirt particles and water. The emulsion is also known as micelle.

જવાબ : The second member of alkyne family is propyne. Its structural formula is H3C—C = CH.

જવાબ : Ethyl ethanoate (CH₃COOC₂H₅) is formed by esterification reaction. It has fruity smell.

જવાબ : The compound is ethanoic acid also called acetic acid.

જવાબ : Yellow soot is obtained when the holes of the burner are not clean. The combustion is incomplete. The yellow – soot or yellow flame is because of unburnt carbon particles.

જવાબ : No, it is not possible because detergents give lather with both soft and hard waters.

જવાબ : Methanol which is highly poisonous is added in small amount to ethanol in order to make it unfit for drinking purposes. The mixture is called methylated spirit or denatured alcohol.

જવાબ : Ground nut oil is unsaturated in nature.

જવાબ : Dip a strip of blue litmus paper in the solution of ethanoic acid. Its colour will change to red.

જવાબ : The hydrocarbon is unsaturated. It is either an alkene or alkyne.

જવાબ : The compounds C₄H₁₀ (butane) and C₆H₁₄ (hexane) are saturated hydrocarbons. They correspond to the molecular formula C_nH_2n+2.

જવાબ : The element is carbon. This is because of very small size of carbon atom (77 pm) and high strength of C—C bond (355 kj mol^-1).

જવાબ : The hydrocarbons are C₂H₄ (ethene) with formula C_nH_2n and C₃H₄ (propyne) with formula C_nH_2n-2 both are unsaturated.

જવાબ : (i) —OH
(ii) —CHO
(iii) —COOH.

જવાબ : (a) In favour of‘Alcohol-free world’:

• Alcohol drinking lowers inhibitions which leads to increased violence and crime in the society.
• A liver disease ‘cirrhosis’ caused by alcohol can lead to death.
• Drunken driving leads to increased road accidents.

• Alcohol is used for making some medicines like cough syrups, tincture iodine, some tonics, etc.
• Mixed with petrol, it is now being used as a fuel for light vehicles.
• It is used for making antifreeze material for cooling engines of vehicles.

• By writing slogan
• Through debates
• By writing articles
• By role plays/skits

જવાબ : Detergents chemically are sodium or potassium salts of sulphonic acid of benzene or alkene.
Merits:
(i) They work well with hard water.
(ii) They are more effective than soaps.
Demerits:
(i) They are expensive.
(ii) Some of them having branching are non-biodegradable, therefore create water pollution.
Detergents are suitable for hard water having  Mg²⁺ and Ca²⁺ ions because they do not form insoluble salts with Mg²⁺ and Ca²⁺ ions.

જવાબ : oaps are sodium or potassium salts of fatty acids having — COONa group. Detergents are
sodium or potassium salts of sulphonic acids having — SO₃Na and — SO₄Na group. Cleansing action of soap: Soap molecules consist of a large hydrocarbon tail which is hydrophobic (water-hating or water repelling) with a negatively charged head which is hydrophilic (water-loving) as shown in figure.

When a soap is dissolved in water, the molecules associate together as clusters called micelles in which water molecules, being polar in nature, surround the ions and the hydrocarbon part of the molecule attracts grease, oil and dirt.

જવાબ : The series of organic compounds having same functional group and similar chemical properties is called homologous series.
Each member differs from successive member by —CH₂— group. The difference in molecular weight between two successive members is 14 u.
Characteristics:
(i) It has same general formula, from which, all members can be derived.
(ii) They have similar chemical properties.
C₂H₄, CH₂=CH₂, Ethene is first member of alkene series.

જવાબ : (i) It is because carbon has four valence electrons, it cannot gain or lose four electrons because high energy is needed. It can only share four electrons.
(ii) It is due to strong covalent bonds and compact structure of diamond.
(iii) It is due to presence of free electrons in graphite because each carbon is linked to three more carbon atoms.
(iv) It is due to high percentage of carbon, it burns with sooty or smoky flame.
(v) Kerosene oil is mixture of saturated hydrocarbons therefore does not decolourise bromine water.

જવાબ : (a) (i)-Catenation (ii) Tetravalency
(b) It is because large number of molecular ions of soaps get aggregated and form colloidal solution. Soap has hydrophobic tail (hydrocarbon) which dissolves in hydrocarbon part and hydrophilic part dissolves in water. Ethanol is non-polar solvent therefore micelles are not formed because hydrocarbon part gets attracted towards ethanol and ionic end will not dissolve in alcohol.

જવાબ :
When unsaturated hydrocarbons are heated with hydrogen in the presence of nickel as catalyst, saturated hydrocarbons are formed. If the starting unsaturated hydrocarbons are liquids, they will change into solids. Vegetable oils are hydrogenated to form vegetable ghee. Plants are natural sources of vegetable oils which can be hydrogenated.

જવાબ : Bromine water test – is used to differentiate between the unsaturated compounds (like alkenes and alkynes) and the saturated compounds. For this purpose, bromine is used in the form of bromine water. A solution of bromine in water is called bromine water. Bromine water has a red-brown color due to the presence of bromine in it. When bromine water is added to an unsaturated compound, then bromine gets added to the unsaturated compound and the red-brown color of bromine water is discharged. So, if an organic compound decolorizes bromine water, then it will be an unsaturated hydrocarbon (containing a double bond or a triple bond), but saturated hydrocarbon (alkanes) do not decolorize bromine water.

જવાબ : Micelle formation takes place because of the dirt particles in water and clean water. There are two mediums that are involved: one is pure water and the other being dirt (also called as impurities). The soap also has two mediums:

જવાબ :  

જવાબ : The compound ‘A’ with formula C₃H₈(propane) is a saturated hydrocarbon and corresponds to general formula C_nH_2n+2. The compound ‘B’ with formula C₃H₆ (propene) is an unsaturated hydrocarbon and corresponds to general formula C_nH_2n. It has a double bond (C=C) and is therefore, unsaturated.

The compound ‘B’ will take part in the addition reactions. As a result, double bond will change to single bond. For example,

The addition reaction is quite useful in the hydrogenation of oils i.e., to convert edible oils like ground nut oil and cotton seed oil which are unsaturated in nature into solid fats which are of saturated nature.

જવાબ : (a) Carboxylic acids (organic acids) are less ionised in solution as compared to mineral acids (HCl, HNO₃, H₂SO₄ etc.) Due to this reason, these are weaker acids than the mineral acids.
(b) Take a small volume of ethanoic acid in a tube. Add a few drops of sodium carbonate (Na₂CO₃) solution prepared in water to the tube. A colourless gas with brisk effervescence will evolve. When the gas is passed through lime water, it will become milky.

(c) The cleansing action of soap is based on its tendency to act as a bridge between water and oil drops containing dirt particles. As a result, oil and water get mixed. They form a stable emulsion also called micelle. This helps in removing oil drops containing dirt particles from clothes. The clothes become clean.

જવાબ : (a) Homologous series represent different families of organic compounds into which these are divided. Two characteristics of homologous series are listed.

1. All the members in a particular homologous series of family have the same characteristic functional group. For example, in organic acids, the functional group is carboxyl group (—COOH).
2. Any two consecutive members in a particular family have the same common difference of CH₂ in their molecular formulae. For example, the first three members of the family of alkanes are : CH₄ (methane), C₂H₆ (ethane) and propane (C₃H₈).

(b) On adding a 5% solution of alkaline potassium permanganate to ethanol, it will be oxidised to ethanoic acid.
The pink colour of the solution will get discharged upon warming.

(c) A carboxylic acid gives a brisk effervescence when an aqueous solution of sodium hydrogen carbonate (NaHCO₃) is added to it. This is due to the evolution of CO₂ gas. However, alcohol will not give any reaction.

જવાબ : We all know that soap is used to remove dirt and and grime from substances. Generally dirt and grime get stuck because they have an oily component, which is difficult to remove, by plain brushing or washing by water. A soap molecule has two parts, a head and a tail i.e. the long chain organic part and the functional group –COO^– Na⁺.
A soap molecule has a tadpole like structure shown below.
The organic part is water insoluble but is soluble in organic solvents or in oil or grease. The ionic part is soluble in water, as water is a polar solvent. When soap is added to water in which dirty clothes are soaked, the two parts of the soap molecule dissolve in two different mediums. The organic tail dissolves in the dirt, grime or grease and the ionic head dissolves in water. When the clothes are rinsed or agitated, the dirt gets pulled out of the clothes, by the soap molecule. In this way soap does its cleaning work on dirty and grimy clothes or hands.

The soap molecules actually form a closed structure because of mutual repulsion of the positively charged heads. This structure is called a micelle. The micelle pulls out the dirt and grime more efficiently.

જવાબ : Bromine water test can be used to differentiate chemically between butter and cooking oil. Add bromine water to a little of cooking oil and butter taken in separate test tubes. a. Decolourising of bromine water by cooking oil (unsaturated compound)
b. Butter (saturated compound) does not decolourise bromine water

જવાબ : Alkenes and alkynes (unsaturated hydrocarbons) undergo addition reactions. From the above hydrocarbons C₂H₂ is an alkyne, whereas C₃H₆ is an alkene. So, C₃H₆ and C₂H₂ will undergo addition reactions.

જવાબ : The precipitate form of scum is formed when soap is used for washing clothes. With hard water, a large amount of soap is wasted in reacting with the calcium and magnesium ions of hard water to form an insoluble precipitate. The precipitate form formed by the action of hard water on soap, sticks to the clothes being washed and interferes with the cleaning ability of the additional soap. This makes the cleaning of clothes difficult.

જવાબ : Micelle formation takes place when soap is added to water. This is because when soap is added to water in which dirty clothes are soaked, the two parts of the soap molecule dissolves in two different mediums. The organic tail dissolves in the dirt, grime or grease and the ionic head dissolves in water. When the clothes are rinsed or agitated, the dirt gets pulled out of the clothes in the water by the soap molecule. In this way the soap does its cleaning work on dirty and grimy clothes or hands.
The soap molecules actually form a closed structure because of mutual repulsion of the positively charged heads. This structure is called a micelle.

જવાબ : (i) Ethanol has a pleasant smell whereas ethanoic acid has the smell of vinegar.
(ii) Ethanol has a burning taste whereas ethanoic acid has a sour taste.
(iii) Ethanol has no action on litmus paper whereas ethanoic acid turns blue litmus paper red.
(iv) Ethanol has no reaction with sodium hydrogencarbonate but Ethanoic acid gives brisk effervescence with sodium hydrogencarbonate.

જવાબ : Homologous series is a series of compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass. For example, methane has a lower boiling point than ethane since it has more intermolecular forces with neighbouring molecules. This is because of the increase in the number of atoms making up the molecule.

જવાબ : When a dirty cloth is put in water containing dissolved soap, then the hydrocarbon end of the soap molecules in micelle attach to the oil or grease particles present on the surface of dirty cloth. In this way the soap micelle entraps the oily or greasy particles by using its hydrocarbon ends. The ionic ends of the soap molecules in the micelles, however, remain attached to water. When the dirty cloth is agitated in soap solution, the oily and greasy particles present on its surface and entrapped by soap micelles get dispersed in water due to which the soap water becomes dirty but the cloth gets cleaned. The cloth is cleaned thoroughly by rinsing in clean water a number of times.

જવાબ : We know that Butter is a saturated carbon compound while cooking oil is an unsaturated carbon compound. An unsaturated compound decolourises bromine water, while a saturated compound cannot decolourise it. So we can distinguish chemically between a cooking oil and butter by the bromine water. Add bromine water to a little of cooking oil and butter taken in separate test-tubes.

• Cooking oil decolourises bromine water showing that it is an unsaturated compound.
• Butter does not decolourise bromine water showing that it is a saturated compound.

જવાબ :

a. Ester
b. Catenation
c. Detergent

જવાબ :

a. Ethene
b. Isomers
c. Diamond
d.  Hydrocarbons

જવાબ :

(a) – (iii)
(b) – (i)
(c) – (iv)
(d) – (ii)

જવાબ :

(a) – (ii)
(b) – (iii)
(c) – (iv)
(d) – (i)

જવાબ :

(a) – (iv)
(b) – (i)
(c) – (ii)
(d) – (iii)

જવાબ :

(a) – (iv)
(b) – (iii)
(c) – (ii)
(d) – (i)