WBBSE Class 10 Physical Science Solutions Chapter 8.6 Organic Chemistry

Detailed explanations in West Bengal Board Class 10 Physical Science Book Solutions Chapter 8.6 Organic Chemistry offer valuable context and analysis.

WBBSE Class 10 Physical Science Chapter 8.6 Question Answer – Organic Chemistry

Very Short Answer Type Questions :

Question 1.
What is the common element of organic compounds ?
Answer:
Carbon is the common element of organic compounds.

Question 2.
What is Catenation ?
Answer:
Catenation is the property of organic compounds where a large number of carbon atom link together.

Question 3.
What is monomer ?
Answer:
Monomer is a small organic molecule that joins with other similar molecules to form a polymer.

Question 4.
What is mustard gas ?
Answer:
It is a gas produced from ethylene.

Question 5.
What is a primary alcohol ?
Answer:
It is a type of alcohol in which the carbon atom bearing the OH group con­tains at least 2 hydrogen atoms.

Question 6.
What is an unsaturated hydrocarbon ?
Answer:
It is an organic compound in which at least two carbon atoms join by covalent double or triple bond.

Question 7.
What is a saturated hydrocarbon ?
Answer:
It is hydrocarbon in which carbon atoms are linked with single covalent bond.

Question 8.
What is a functional group ?
Answer:
Functional group is a group of atoms present in organic compounds of a class determining almost the common properties of the compounds.

Question 9.
What type of bonding exists in organic compounds ?
Answer:
Covalent type of bonding exists in organic compounds.

Question 10.
What is DNA ?
Answer:
DNA stands for deoxyribonucleic acid.

Question 11.
What are biomolecules ?
Answer:
These are some organic molecules involved in metabolic process.

Question 12.
What is isomerism ?
Answer:
Isomerism is the property due to which a group of organic compounds of same molecular formula but differ from each other in their structural formulae and properties.

Question 13.
State one use of methane.
Answer:
Use of methane : As a domestic and industrial fuel.

Question 14.
State one use of ethylene.
Answer:
Use of ethylene : To prepare polythene.

Question 15.
State one use of acetylene ?
Answer:
Use of acetylene : To produce benzene, artificial rubber.

Question 16.
What are the essential two components of amino acids ?
Answer:
The essential two components of amino acids are carboxyl (-COOH) and an amino (-NH₂) group attached to the same carbon atom.

Question 17.
Name and write down the formula of a ketone.
Answer:
The name of a ketone is acetone (CH₃COCH₃).

Question 18.
Which gas burns in a carbide gas lamp ?
Answer:
Acetylene gas burns in a carbide gas lamp.

Question 19.
What change of litmus will occur in alcohol ?
Answer:
Alcohol is a neutral compound, so no change of colour of a litmus paper dipped in it occurs.

Question 20.
What is the functional group of alcohol ?
Answer:
Hydroxyl group (-OH) is the functional group of alcohol.

Question 21.
Which gas is known as marsh gas ? Why is it called so ?
Answer:
Methane gas is known as marsh gas. It is present in marshy (i.e. always wa­tery) lands, so it is called marsh gas.

Question 22.
Name three hydrocarbons available from coal gas.
Answer:
Methane, ethylene, acetylene are three hydrocarbons available from coal gas.

Question 23.
Give two examples of alkyne with corresponding formulae.
Answer:
Two alkyne :

• Acetylene (HC ≡ CH)
• Propyne (CH₃– C = C – H)

Question 24.
What is alkane ? Write down its general formula.
Answer:
An alkane is an open-chained saturated hydrocarbon.
The general formula of alkane : C_nH_{2n + n}(n – integer)

Question 25.
Name and draw structural formula of a saturated organic compound.
Answer:
Saturated organic compound :

Question 26.
Name and draw structural formula of an unsaturated organic compound.
Answer:
Unsaturated organic compound : Ethylene

Question 27.
Name and draw structural formula of an aromatic compound.
Answer:
Aromatic compound Benzene

Question 28.
Name three organic compounds used in daily life.
Answer:
Three organic compounds used in dialy life : Carbohydrates, proteins, glucose.

Question 29.
Name two plymers.
Answer:
Two polymers are :

• Polythene
• Teflon

Question 30.
What is hydrocarbon ? Name the simplest hydrocarbon.
Answer:
Hydrocarbon : A binary compound formed of carbon and hydrogen by covalency is called hydrocarbon.
Simplest hydrocarbon : Methane (CH₄).

Question 31.
What is PVC ? State its use.
Answer:
PVC : It is polyvinyl chloride, its monomer is vinyl chloride.
Uses of PVC : To prepare water and rain pipes, toys etc.

Question 32.
Why butane is used in LPG ?
Answer:
Butane is the most convenient fuel for domestic use because both isomers of butane (n-butane and isobutane) are easily liquefied and can be transported in steel cylinders easily.

Question 33.
How does the boiling point of alkane changes ?
Answer:
The boiling point generally increase with increase in the number of carbon atoms.

Question 34.
What is mineral oil ?
Answer:
Oil obtained from petroleum is called mineral oil.

Question 35.
What is fire damp ?
Answer:
The gas responsible for explosions in coal mines is methane and is also known as fire damp.

Question 36.
Why are the alkenes more reactive than alkanes ?
Answer:
The chemical reactivity of alkenes are mote than alkanes due to presence of π-electron in alkenes.

Question 37.
How many s and p bonds are present in ethylene ?
Answer:
Ethylene has one π-bond and five σ-bonds.

Question 38.
Why the hydrogens of alkynes are acidic in nature ?
Answer:
Hydrogen has appreciable acidic character when bond to a carbon atom of a(C = C) triple bond (in case of alkyne).

Question 39.
What are the end products of combustion of hydrocarbons ?
Answer:
End products of combustion of all hydrocarbons are carbon dioxide and water.

Question 40.
What is the most oxidised form of hydrocarbon ?
Answer:
RCOOH (R = alkyl group) represents the most oxidised form of hydrocarbons.

Question 41.
What is sabatier and senderens reaction ?
Answer:
Hydrogenation of unsaturated aliphatic hydrocarbons in presence of nickel catalyst is called sabatier and senderens reaction.

Question 42.
What is the condition for halogenation of alkanes ?
Answer:
Halogenation of alkanes does not occur in absence of light or heat.

Question 43.
What is aldose ?
Answer:
Carbohydrate containing aldehyde group is called aldose.

Question 44.
What is ketose ?
Answer:
Carbohydrate containing keto group is called ketose.

Question 45.
Give an example of a monosaccharide.
Answer:
Glucose (C₆H₁₂O₆)

Question 46.
Give an example of polysaccharide.
Answer:
Starch.

Question 47.
What is pyrofax ?
Answer:
Propane is used as a fuel under the name pyrofax.

Question 48.
What is an artificial camphor ?
Answer:
Hexachloroethane is called artificial camphor.

Question 49.
What is TEL ?
Answer:
TEL is commonly used antiknock compound tetraethyl lead, [(C₂H₅)₄ Pb].

Question 50.
What is AK – 33X ?
Answer:
To avoid lead pollution, a new compound called AK – 33X (cyclopentadienyl manganese carbonyl) is used as an antiknock these days.

Question 51.
What is dextrose ?
Answer:
Glucose is called grape sugar or dextrose.

Question 52.
What is fruit sugar ?
Answer:
Fructose is called laevolase or fruit sugar and is the sweetest sugar.

Question 53.
What is milk sugar ?
Answer:
Lactose is known as milk sugar.

Question 54.
What is amylum ?
Answer:
Starch is called amylum.

Question 55.
State an example of globular protein.
Answer:
Insulin is an example of globular protein.

Question 56.
What is nucleotide ?
Answer:
Both DNA and RNA are polymers of a basic repeating unit, called a nucle­otide.

Question 57.
What is the sugar present In RNA ?
Answer:
Sugar present in RNA is ribose.

Question 58.
What is the sugar present in DNA ?
Answer:
Sugar present in DNA is 2-deoxyribose.

Question 59.
What are the main functions of nucleic acids ?
Answer:
Main functions of nucleic acids are the direct synthesis of protein in living cells and transference of genetic information.

Question 60.
Who discovered the double helix structure of DNA ?
Answer:
The double helix structure of DNA was proposed by Watson and Crick (1953).

Question 61.
What is called gene ?
Answer:
DNA sequence that acts as a code for a specific protein or a polypeptide is called gene.

Question 62.
What is called an anabolism ?
Answer:
Anabolism is the process in which macro molecules are synthesised by the cell.

Question 63.
What is called catabolism ?
Answer:
Catabolism is the process in which macro molecules break into smaller ones.

Question 64.
What is metabolism ?
Answer:
Metabolism is the combination of anabolism and catabolism.

Question 65.
What is proteases ?
Answer:
Proteases is the breakdown of large protein molecules into peptides.

Question 66.
Who converts peptides into amino acids ?
Answer:
Peptidases convert peptides into amino acids.

Question 67.
What is soda lime ?
Answer:
Soda lime is a mixture of sodium hydroxide and calcium oxide (NaOH + CaO).

Question 68.
What is the source of acetylene ?
Answer:
The source of acetylene is calcium carbide (CaC₂) from which it is obtained by the action of water at ordinary temperature.
CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂.

Question 69.
Name one biodegradable polymer.
Answer:
One biodegradable polymer is cellulose.

Question 70.
Name the hydrocarbon formed when ethanol is heated with concentrated H₂SO₄
Answer:
When ethanol is heated with concentrated H₂SO₄, ethene (or ethylene) is formed.

Question 71.
What is the common name of ethyne?
Answer:
The common name for ethyne is acetylene.

Question 72.
What is the term used for the compounds which have same molecular formula but different structures?
Answer:
They are called isomers.

Question 73.
What is next homologue of C₂H₅OH?
Answer:
The next homologue of C₂H₅OH (Called ethanol or ethyl alcohol) is C₂H₇OH (propanol).

Question 74.
How is biopolymer protein biodegraded in nature?
Answer:
Proteins are degraded by some specific enzymes produced by some particular Phy. Sc.bacteria (e.g. Bacillus subtilis, Bacillus mycoides, Bacillus vulgaris etc) through ammonification.

Question 75.
How many hydrogen atoms are there in alkyne containing three carbon atoms?
Answer:
The general formula of alkyne is C_nH_2n-2
Here, n = 3
∴ Number of hydrogen atoms = 2n-2 = (2×3)-2=4

Question 76.
What is power alcohol?
Answer:
In countries having shortage of petrol, a mixture of petrol (80%), ethanol (20%) and benzene is used as fuel. This petrol mixed with alcohol is known as power alcohol.

Question 77.
Name two functional groups one containing carbon atom and the other devoid of carbon.
Answer:
Carbon containing functional group : carboxyl

Functional group devoid of carbon : Amino

Question 78.
Give the structural formula of propanal.
Answer:
CH₃ – CH₂ -CHO

Short Answer Type Questions :

Question 1.
What is organic chemistry ?
Answer:
Organic chemistry : All carbon containing compounds except oxides of carbon, metal carbonate, bicarbonate, hydrogen cyanide and metallic cyanides are organic compounds and the chemistry of organic compounds is called organic chemistry.

Question 2
What is Biochemstry ?
Answer:
Biochemistry : It is the branch of chemistry which deals with the com¬position and behaviour of living system.

Question 3.
What are Biomolecules ?
Answer:
Biomolecules : These are the macro-molecules like carbohydrates, amino acids, proteins, vitamins, fats, RNA, DNA etc., which are essential for the continuation of life process of biological species like plants and animals (including human beings) are called biomolecules.

Question 4.
What are Carbohydrates ?
Answer:
Carbohydrates These are the polyhydroxy aldehydes or ketones or these are the compounds which on acidic hydrolysis give polyhydroxy aldehydes or ketones. Their molecules are composed of carbon, hydrogen and oxygen. Carbohydrates are mainly used as food which give us energy to work.

Question 5.
What are Monosaccharides ?
Answer:
Monosaccharides : These are the compounds such as glucose and fructose which do not break into more simpler compounds on hydrolysis.

Question 6.
What are Disaccharides ?
Answer:
Disaccharides : These are the compounds which on hydrolysis give two monosaccharide units.
[Sucrose, Moltose and lactose (milk sugar)]

Question 7.
What are Polysacharides ?
Answer:
Polysaccharides : These are the compounds which on hydrolysis produce very large number of monosaccharide molecules. Cellulose and starch are two important examples of polysaccharides.

Question 8.
What is Moltose ?
Answer:
Moltose : It is obtained by the partial hydrolysis of starch by enzyme diastase present in malt.

Question 9.
What is Lactose ?
Answer:
Lactose : It occurs in the milk of all animals cow’s milk contains about 5% Lactose while human milk contains about 7% lactose.

Question 10.
What is Cellulose ?
Answer:
Cellulose It is the main structural material of wood and other plants. Cotton is about 80% cellulose.

Question 11.
What is Glycogen ?
Answer:
Glycogen : It is a higher sugar stored in liver. In case of emergency, this gets hydrolysed to glucose which then gets oxidised to produce energy.

Question 12.
What are Amino acids ?
Answer:
Amino acids : These are organic compounds containing both amino and carboxylic group in their molecules. They are represented by the general formula.

Question 13.
What are essential amino acids ?
Answer:
Essential amino acids : Human body can synthesis 10 out of 20 a-amino acids found in proteins. The remaining 10 must be present in our diet and are called essential amino acids.

Question 14.
What is Zwitter ion ?
Answer:
Zwitter ion In aqueous solution, the acidic carboxyl group donates a proton to the basic amino group to form an internal salt called a dipolar ion or zwitter ion. Although it is neutral overall, it contains both a positive and a negative charge.

Question 15.
What are Peptides ?
Answer:
Peptides These are condensation products of self-amides formed by the reaction of two or more amino acid molecules.

Question 16.
What is peptide linkage ?
Answer:
Peptide linkage : The bond

between the carboxyl group of an acid molecule and nitrogen of the other amino acid molecule is known as the peptide bond or peptide linkage.

Question 17.
What are Proteins ?
Answer:
Proteins These are complex nitrogeneous substances present in all forms of living matter. These are obtained by the condensation polymerisation of a-amino acids through the formation of peptide bonds. Actually proteins are polypeptides with very high molecular weights (more than 10,000). These are formed by the combination of more than 100 molecules of amino acids.

Question 18.
What is Denaturation ?
Answer:
Denaturation : After coagulation, proteins lose their physiological activity and certain other properties. This phenomenon is known as denaturation.

Question 19.
What are Enzymes ?
Answer:
Enzymes : These are also proteins which acts as catalyst in many bio-chemical reactions. Enzymes are specific in action due to their specific structural arrangement.

Question 20.
What is the biuret test ?
Answer:
Biuret test : To alkaline solution of proteins add a dilute solution of CuS04. Formation of violet colour confirms proteins.

Question 21.
What are Vitamins ?
Answer:
Vitamins : These are the biomolecules needed in small quantities, that regulate many biochemical function and prevent the development of many deficiency diseases.

Question 22.
What are Fats ?
Answer:
Fats : These are organic compounds composed of carbon, hydrogen and oxygen. They are made of glycerol and fatty (organic) acids. Fats may be of animal or vegetables origin.

Question 23.
What are the types of simple proteins ?
Answer:
Types of simple proteins :

• Albumins — e.g. milk, serum etc.
• Globumins — e.g. egg yolk, tissues etc.
• Glutemins — e.g. wheat, rice etc.
• Prolamins — e.g. barli, wheat etc.
• Scleroproteins — e.g. keratin, fibroin etc.

Question 24.
State examples of conjugated proteins and derived proteins.
Answer:
Conjugated proteins :
(a) Phosphoproteins
(b) Glycoproteins
Derived proteins : This type of protein is obtained after the partial hydrolysis of protein of very high molecular weight by acid, base or enzyme to simpler proteins.

Question 25.
What is DNA ?
Answer:
DNA : It is deoxyribonucleic acid. DNA molecule contains three different chemical constituents :
(a) Phosphoric acid
(b) Deoxyribose
(c) Pyridine like base adenine and guanine, pyrimidine like base thymine and cytosine. DNA consists of two strands of polynucleotides coiled around each other by hydrogen bond in the form of a double helix.

Question 26.
What is RNA ?
Answer:
RNA : It is consisted by ribose along with phosphoric acid and bases. In pyrimidine base uracil is present instead of thymine in RNA. RNA carries the message of DNA and acts accordingly. Mainly there are three types of RNA :

• m-RNA
• t-RNA
• r-RNA

t-RNA and m-RNA have taken an important role in the protein synthesis.

Question 27.
What is Catenation ?
Answer:
Catenation : The property by virtue of which carbon forms covalent linkage chains is called catenation.

Question 28.
What is Functional group ?
Answer:
Functional group An atom or a group of atoms which being present within the molecule of an organic compound, causes the compound to function or behave chemically in a particular way is called a functional group, e.g. alcohol (-OH), aldehyde (-CHO)

Question 29.
What are Hydrocarbons ?
Answer:
Hydrocarbons : These are organic compounds containing only carbon and hydrogen atoms in their molecules. They are divided into two classes.

• Saturated hydrocarbons
• Unsaturated hydrocarbons.

Question 30.
What are saturated hydrocarbons ?
Answer:
Saturated hydrocarbons : Saturated hydrocarbons are those in whose molecules the carbon atoms are joined to each other by single bond and the remaining valencies of the carbon atoms are satisfied by hydrogen atoms. e.g. Methane (CH₄), Ethane (C₂H₆).

Question 31.
What are unsaturated hydrocarbons ?
Answer:
Unsaturated hydrocarbons :
The compounds in which carbon atoms are connected among themselves by double bond or triple bond are called unsaturated hydrorcarbons.

Question 32.
What are Alkenes ?
Answer:
Alkenes Those unsaturated hydrocarbons containing double bond (=) between two adjacent carbon atoms in their molecules are called as alkenes.

Question 33.
What are Alkynes ?
Answer:
Alkynes : Those unsaturated hydrocarbons containing triple bonds (s) be­tween two adjacent carbon atoms in their molecules are called as alkynes.

Question 34.
What are Cyclic compounds ?
Answer:
Cyclic compounds : Organic compounds containing closed of atoms are called cyclic compounds. Cyclic compounds are of two types,

• Homocyclic compounds
• Heterocyclic compounds.

Question 35.
What are Homocyclic compounds ?
Answer:
Homocyclic compounds These are the compounds where all the atoms present in the cyclic compounds in the series are carbon atoms. These are of two types,

• Aromatic compounds
• Alicyclic compounds.

Question 36.
What are Aromatic compounds ?
Answer:
Aromatic compounds Aromatic compounds are those which have a hexagonal ring structure formed by six carbon atoms bonded each other by a single or double bonds.

Question 37.
What are Alicyclic compounds ?
Answer:
Alicyclic compounds : These compounds are the cyclic or ring compounds without having any benzene ring.

Question 38.
What are Heterocyclic compounds ?
Answer:
Heterocyclic compounds : Sometimes N, O, S atoms are linked along with carbon atoms in series during the formation of closed ring structure. These compounds are called heterocyclic compounds.

Question 39.
What are Homologous series ?
Answer:
Homologous series A homologous series may be defined as a group of compounds in which various members

• have similar chemical properties
• can be represented by the same general formula
• possess the same functional group the different members of homologous series are called homologues and the phenomenon is called homology.

Question 40.
What is Isomerism ?
Answer:
Isomerism In organic chemistry when the same molecular formula rep­resents two or more compounds which differ in their physical and chemical properties, then such compounds are called isomers and the phenomenon is called isomerism.

Question 41.
What are Structural isomers ?
Answer:
Structural isomers : Isomers that have same molecular formula but differ in the arrangement of atoms within the molecule are known as structural isomers.

Question 42.
What are Stereoisomers ?
Answer:
Stereoisomers The isomers that have the same constitution but different in the spatial arrangement of their atoms are called stereoisomers.

Question 43.
What are the types of structural isomers ?
Answer:
(a) Chain isomerism :

Question 44.
What is the “will-o-the wisp”?
Answer:
In marshy lands and in sewage sludge, methane gas is set free by the bacterial decomposition of vegetable matters under water. Methane itself is highly inflammable. Moreover, a little phosphine (PH₃) and diphosphine (P₂H₄) accompany the gas and make it spontaneously inflammable. Thus the ‘will-o-the-wisp’ results.

Question 45.
Draw position isomers of butene(C₄H₈)
Answer:
Position isomers of butene (C₄H₈)are shown below :

Question 46.
Name an organic compound which is
(a) used to illuminate country houses
(b) used to make polythene
(c) poisonous containing -OH group
(d) consumed as a drink
Answer:
(a) Acetylene
(b) Ethene
(c) Methanol
(d) Ethanol.

Question 47.
Which gas is produced when sodium carbonate reacts with acetic acid ?
Answer:
Acetic acid decomposes sodium carbonate to liberate CO₂
2CH₃COOH + Na₂O₂CO₃→ 2CH₃COONa + CO₂↑+ H₂O

Question 48.
How can traces of ethylene mixed with methane be identified?
Answer:
When the gas mixture is passed through reddish-brown solution of bromine in CCl₄the solution becomes colourless due to the formation of colourless 1, 2-dibromoethane if the gas mixture contains ehhylene.

This is a test for detecting ethylene and ethylenic unsaturation in the organic compounds.

Short Answer Type Questions 

Question 1.
State the difference between organic and inorganic compounds.
Answer:
Difference between organic and inorganic compounds :

Organic Compounds

• The catenation property of carbon atoms among themselves and other atoms give rise to limidess number of organic compounds.
• They form covalent bonds.
• They have low melting and low boiling point.
• These are not ionised at all.
• They show isomerism.
• They are soluble in organic solvents like alcohol, ether etc.

Inorganic compounds

• Due to absence of catenation property of its atoms the number of inorganic compounds formed by the rest of the elements is not so large .
• Inorganic compounds may be covalent or electrovalent.
• They have high melting and boiling point.
• Most of the inorganic compounds are electrolytes.
• They have high rate of reaction.
• Very few Inorganic compounds show isomerism.
• They are soluble in ionising solvent like water, but are insoluble in organic solvent.

Question 2.
State the following facts of Methane.
(i) Source/preparation
(ii) Important reaction
(iii) Uses
(iv) Structure
Answer:
The following facts of methane :

Question 3.
State the following facts of Ethylene.
(i) Source/preparation
(ii) Important reaction
(iii) Uses
(iv) Structure
Answer:
The following are of ethylene.

Question 4.
What are Polymers and what are Monomers. Give few examples.
Answer:
Polymer : Under suitable conditions, many molecules of alkene and alkyne combine together forming a very high molecular weight compound known as polymer. The small moleculers are known as monomers and this process is known as polymerisation.

Some common polymers

Question 5.
What are Biodegradable and Non-biodegradable materials.
Answer:
Biodegradable materials : Materials of vegetable and animal origin invariably decay and decompose into CO₂, H₂O, N₂ or NH₃ by the com­bined action of sometimes of natural agencies like air, water, subshine etc. These are called biodegradable materials.

Non-biodegradable materials : Synthetic materials like plastics, polythene, teflon, PVC etc, are not decomposed by these natural agencies even on for a long time. These are called non-biodegradable materials.

Question 6.
State the following facts of acetylene.
(i) Source/preparation
(ii) Important reaction
(iii) Uses
(iv) Structure
Answer:
The following facts of acetylene

Question 7.
Discuss about the hazards of using Polyethylene, Teflon and PVC.
Answer:
Explanation : Polyethylene, teflon and PVC are non-biodegradable material. These substances do not decompose or decay naturally on long standing. These articles are usually left in soil or water. This practice causes pollution of soil, water and air.

(a) Solid wastes containing PVC when incinerated (consumed by fire) produce the highly toxic substance dioxin. Soil contains two main bios, detrivore and decomposer which analyse or detoxify many bio-degradable substances.

(b) But the polyethylene, teflon, PVC etc. are not bio-digradable substances, they rather spoil detrivore and decomposer of soil. In presence of air and water these synthetic substances excreate some poisonous chemicals in top soil spoiling the minerals necessary for plants.

Question 8.
State possible alternatives to avoid the hazards due to polythene materials.
Answer:
Possible alternatives : The possible alternative that can eliminate the hazards of using polythene is to restrict their uses to a minimum extent. In places of polythene bags for carrying purchases, bags made of cloth, paper or jute should be used. Paper or dry leaf packets should be used instead of polythene packets to carry sweets and other edible solid materials.

The use of polythene glass, tea-cups etc. should be discontinued, and those made of hard paper or earthenwares should be used instead. Polythene sheets for covering should be replaced by thin terpaulin, waxed paper or tar-laminated papers, jute cloth etc.