GSEB Solutions for Class 10 Science and Technology – Organic Compounds (English Medium)
GSEB SolutionsMathsScience
Question 1:
Select the proper choice from the given multiple choices :
Question 1.1:
What is called the compounds possessing (-CHO) functional group ?
Solution :
B. Aldehyde
-CHO is a functional group of aldehydes. Aldehydes are named by adding the suffix ‘al’ to the corresponding name of the hydrocarbon from which it is derived.
Question 1.2:
Which functional group is possessed by carboxylic acid ?
Solution :
B. -COOH
Carboxylic acids contain the -COOH functional group. They are generally weak acids.
Question 1.3:
‘or suffix is attached with which group in nomenclature ?
Solution :
C. -OH
Compounds which contain the -OH or hydroxyl group are called alcohols. They are named by adding the suffix ‘ol’ to the corresponding name of the hydrocarbon from which it is derived.
Question 1.4:
Which functional group is there in methyl ethanoate ?
Solution :
D. Ester
Methyl ethanoate is formed by the reaction between a carboxylic acid and an alcohol. It contains an ester (-COOR) as a functional group.
Question 1.5:
Which of the following compounds is obtained by fermentation reaction of molasses ?
Solution :
B. Ethanol
The fermentation of sugars present in molasses by the action of enzymes such as zymase results in the production of the alcohol ethanol.
Question 1.6:
What is called the solution ethanol containing 5% water ?
Solution :
C. Rectified spirit
Ethanol with 5% water is called rectified spirit and is used for making the outer surface of the body germ-free.
Question 1.7:
What is the moleuclar formula of formalin ?
Solution :
C. HCHO
Formalin is the common name of formaldehyde and is also called methanal.
Question 1.8:
Which substance is obtained by reduction of methanal ?
Solution :
C. Methanol
Methanal reacts with dihydrogen gas in the presence of palladium catalyst and gets reduced to methanol.
Question 1.9:
What is prepared by Fisher-Tropsch method ?
Solution :
C. Acetone
In the Fischer-Tropsch process, when a mixture of ethene and water gas is passed over a catalyst like cobalt oxide at 150 bar pressure and 453 K temperature, acetone is obtained.
Ethene Acetone
Question 1.10:
Which of the following is the use of propanone ?
Solution :
A. To remove nail polish
Acetone is also used as a solvent in the laboratory and in the paint industry, and in making artificial leather and synthetic fibres.
Question 1.11:
Which of the following is the reaction occurring between alcohol and carboxylic acid in presence of concentrated H2SO4 ?
Solution :
D. Esterification
The formation of an ester by the reaction of a carboxylic acid with an alcohol is called an esterification reaction.
For example, when ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid, ethyl acetate is formed.
Question 1.12:
Which compound of the following functional groups is having minimum three carbon atoms ?
Solution :
The compound with a functional ketone group has a minimum of 3 carbon atoms. For example, acetone is the simplest ketone with molecular formula CH3COCH3.
Question 1.13:
Which of the following monomers is in polythene
Solution :
C. CH2=CH2
Polythene is a polymer formed by the addition reaction of innumerable molecules (monomers) of ethene with one another.
Question 1.14:
Which of the following is the use of acetic acid ?
Solution :
D. All the given
Acetic acid is used in the preparation of vinegar, to have sour taste in food, as preservatives for foods, as a solvent and reagent in the laboratory and in the preparation of white lead.
Question 1.15:
Which of the following is used in conveyor belts ?
Solution :
D. Neoprene
Neoprene is used in conveyor belts as it is highly non-inflammable because of the presence of a large number of chlorine atoms.
Question 2:
Answer the following questions in brief :
Question 2.1:
Mention the functional groups containing oxygen.
Solution :
The following functional groups contain oxygen:
- Carboxylic acid group
- Ketone group
- Aldehyde group
- Hydroxyl group
- Ester group
Question 2.2:
Explain the fermentation reaction and its importance.
Solution :
The formation of simple substances by the slow decomposition of organic compounds through enzymes in the absence of oxygen is called fermentation.
The formation of curd from milk and the reaction in the dough (khiru) of idli and dhokla are examples of the fermentation reaction.
Fermentation reactions are also used in industries for alcohol production from fruit juices.
Question 2.3:
Write preparation of methanal with equation.
Solution :
Methanal is formed when methanol is oxidised at temperatures of 873 K to 973 K in the presence of a catalyst such as silver oxide or iron oxide.
Question 2.4:
Write properties of methanal.
Solution :
Properties of methanal:
- It is a colourless poisonous gas.
- Its boiling point is 253 K.
- It is soluble in water.
- Methanal is used in the production of methanoic acid by the oxidation of methanal.
Question 2.5:
Write Fisher-Tropsch method with equation.
Solution :
Question 2.6:
Write preparation of ethanoic acid.
Solution :
Question 2.7:
Write the defintion of functional group and give examples of two functional groups.
Solution :
An atom or a group of atoms by which the characteristic reactions of organic compounds are determined is called the functional group.
Different organic compounds with the same functional group show similar chemical reactions.
Examples:
- Carboxylic acid group (-COOH)
- Aldehyde group (-CHO)
Question 2.8:
Explain homopolymer and co-polymers.
Solution :
Homopolymer:
Homopolymers are formed when two or more innumerable simple organic monomers of the same type combine with one another through chemical bonds.
Example: Polythene formed from ethene is a homopolymer.
Co-polymers:
Co-polymers are formed when two or more innumerable simple organic monomers of a different type combine with one another through a chemical bond.
Example: Styrene butadiene rubber is prepared from styrene and butadiene; it is a co-polymer.
Question 2.9:
Explain addition and condensation polymers.
Solution :
Addition polymers:
Polymers which are formed by the combination of chemical bonds of innumerable simple organic monomers with double bonds are called additional polymers.
Example: Polystyrene formed from styrene
Condensation polymers:
When two different types of innumerable simple organic monomers combine with one another by condensation polymerisation and give polymers after the removal of molecules such as water and ammonia are called condensation polymers.
Example: Nylon 6, 6 obtained from hexamethylenediamine and adipic acid
Question 2.10:
Write structures and uses of ethene and vinyl chloride polymer.
Solution :
Question 2.11:
Write uses of polymers.
Solution :
Uses of polymers:
- Making toys and packing bags
- Making flooring tiles, rain coats, hand bags
- Making non-stick cooking vessels and as insulators
- In the manufacture of waterproof clothes, tyres of cars and bikes
- As an insulator in conveyor belts, rollers for printing
- In the manufacture of pipes, paints, fibres like nylon, terrylene, spare parts of automobiles, furniture, combs
- Polymers are used in making synthetic rubber for tubes and tyres of vehicles
- Biodegradable polymers are used in special type of packaging, orthopaedic appliances and in capsules
Question 2.12:
Write the structure and uses of teflon and polyisoprene polymers.
Solution :
Question 3:
Answer the following questions :
Question 3.1:
Write industrial production of ethanol.
Solution :
Two methods are available for industrial production of ethanol:
1. Production of ethanol by fermentation
In industrial fermentation, at first, glucose and fructose are formed by the digestion of fruit juices in the presence of enzyme invertase.
2. Modern method of industrial production
Hydration of ethane in the presence of concentrated sulphuric acid also results in the production of ethanol. This method is more commonly used for the industrial production of ethanol.
Question 3.2:
Write properties of ethanol.
Solution :
Properties of ethanol:
- Pure ethanol is a colourless liquid.
- Its boiling point is 351 K.
- It is highly soluble in water.
- Ethanol is highly combustible. It burns with a blue flame and produces carbon dioxide and water on combustion.
Question 3.3:
What is rubber ? Explain.
Solution :
Rubber is a natural or synthetically prepared polymer. It is highly elastic, resistant to non-polar solvents and gets easily oxidised.
Natural rubber is available from the rubber plant in the form of a colloidal suspension. The elasticity of rubber is maintained between temperatures of 283 K and 333 K.
Question 3.4:
Write uses of ethanol.
Solution :
Uses of ethanol:
- It is used as a solvent in industries, in lacquers and varnish.
- It is used in perfumes and medicine as a solvent.
- It is used as an antiseptic, for dressing and cleaning of boils.
- Ethanol with 5% water is called rectified spirit and is used for making the outer surface of the body germ-free.
Question 3.5:
Give examples of aldehyde and ketone.
Solution :
Examples of aldehydes:
- Formaldehyde
- Propanal
- Ethanal
Examples of ketones:
- Propanone
- Butanone
Question 3.6:
Write oxidation, reduction and addition reaction of methanal with hydrogen cyanide.
Solution :
Oxidation reaction of methanal
Methanal gets reduced in the presence of oxidising substances to form methanoic acid.
Reduction reaction of methanal
Methanal reacts with dihydrogen gas in the presence of palladium catalyst and gets reduced to methanol.
Addition reaction with hydrogen cyanide
In methanal, a double bond is present between carbon and oxygen. Hydrogen cyanide reacts with methanal and forms an addition product methanal cyanohydrins by the addition of groups across the double bond.
Question 3.7:
Write uses of acetone.
Solution :
Uses of acetone:
- Solvent in the laboratory and in the paint industry
- Making artificial leather and synthetic fibres
- As nail paint remover
Question 3.8:
Write uses of ethanoic acid.
Solution :
Uses of ethanoic acid:
- In the preparation of vinegar, to have sour taste in food
- As preservatives for food
- As a solvent and reagent in the laboratory
- In the preparation of white lead
Question 3.9:
What is meant by soap ? Write its preparation.
Solution :
Soap is a sodium or potassium salt of a fatty acid.
Preparation of soap:
Vegetable oil such as groundnut or castor oil or animal fat when heated with sodium hydroxide forms sodium salt of fatty acid, i.e. soap and glycerol. This process of preparing soap is called saponification.
Question 3.10:
What is called esterification reaction ? Explain giving examples.
Solution :
The formation of an ester by the reaction of a carboxylic acid with an alcohol is called an esterification reaction.
For example, when ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid, ethyl acetate is formed.
Question 4:
Answer the following questions in detail :
Question 4.1:
Write names and molecular formulas of first four members of alkanes and their corresponding alcohols.
Solution :
No. | Alkane | Molecular formula | Corresponding alcohol |
1 | Methane | CH4 | Methanol (CH3OH) |
2 | Ethane | C2H6 | Ethanol (CH3CH2OH) |
3 | Propane | C3H8 | Propanol (CH3CH2CH2OH) |
4 | Butane | C4H10 | Butanol (CH3CH2CH2CH2OH) |
Question 4.2:
Write four chemical properties of ethanol.
Solution :
Chemical properties of ethanol:
- Ethanol is highly combustible. It burns with a blue flame and produces carbon dioxide and water on combustion.
Question 4.3:
“Alcohol is harmful as drink.” Explain this statement in detail.
Solution :
- Alcohol-containing drinks have ethanol as the main constituent.
- In small amount, ethanol works as a stimulant. However, an excess amount of ethanol gets absorbed in the blood and can result in unconsciousness and heart failure.
- Oxidation of ethanol forms acetaldehyde in cells, mainly of liver. As a result, a person feels like vomiting or looses balance.
- Alcohol also has an adverse effect on eye-sight, causing blindness, and on the liver, causing cirrhosis.
- Thus, alcohol is harmful as a drink.
Question 4.4:
Write uses of methanal (formaldehyde).
Solution :
Uses of methanal:
- As raw material in the plastic industry
- As a monomer in making bakelite and melamine
- For making dyes, phenol and formaldehyde fibres
- Aqueous solution of methanol is used as an antiseptic and to preserve residues of dead animals
- Urea formaldehyde (UF) is a resin used as foam
Question 4.5:
Write properties of propanone.
Solution :
Properties of propanone:
- It is a colourless liquid with fragrant smell.
- Its boiling point is 329 K.
- It is soluble in water.
- On reduction, propanone gives propan-2-ol in the presence of reducing agents such as sodium borohydride (NaBH4) or lithium aluminium hydride (LiAlH4).
Question 4.6:
Write properties of ethanoic acid.
Solution :
Properties of ethanoic acid:
- Ethanoic acid is a colourless liquid.
- It has a sour smell and is soluble in water.
- The boiling point of ethanoic acid is 391 K.
- Ethanoic acid reacts with highly reactive metals such as sodium and magnesium to form metal acetate and dihydrogen gas. Ethanoic acid is a weak acid.
- When ethanoic acid reacts with a base (e.g. sodium hydroxide), salt (e.g. sodium acetate) and water are formed.
- When ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid, ethyl acetate is formed. This reaction of the formation of an ester by the reaction of a carboxylic acid with an alcohol is called esterification.
Question 4.7:
What is polymer ? Explain in detail.
Solution :
A polymer is a macromolecule formed by the combination of one or more than two types of innumerable simple molecules by chemical bond formation.
The process of formation of polymers is called polymerisation.
For example, polythene is formed by the addition reaction of innumerable molecules of ethene with one another.
Question 4.8:
Write a short note on detergents.
Solution :
Detergents are sodium salts of organic sulphonic acids. They are hydrocarbons possessing the sulphonate (-SO3Na) functional group.
Detergents are effective cleansing agents in hard water too. The calcium and magnesium ions do not precipitate with the soluble ions present in the detergents; thus, the detergent is not wasted.
The structure of detergents consists of two parts – long hydrocarbon chain and negatively charged head.
The hydrocarbon chain is non-polar and is attracted to dirt or stains. The negatively charged head is of the functional group (-SO3Na). It is polarand is attracted towards water molecules.
When a concentrated solution of detergent is applied on dirt or grease, the hydrocarbon part remains attached with the surface containing dirt or oil and the polar head remains in water. The dirt or oil is then dragged by the detergent compound into the water so that water becomes dirty and the surface of cloth becomes clean.
Question 5:
Answer the following questions pointwise :
Question 5.1:
Write in detail classification of polymers.
Solution :
A polymer is a macromolecule formed by the combination of one or more than two types of innumerable simple molecules by chemical bond formation.
Polymers are classified by considering two factors:
1. Classification based on occurrence in nature
- Naturally occurring polymers
- Semi-synthetic polymers
- Synthetic polymers
2. Classification based on polymerisation reaction
- Homopolymers and co-polymers
- Addition and condensation polymers
- Biopolymers
Question 5.2:
Write short notes-polyester and polyamide.
Solution :
Polyester:
Polyester is a type of condensation polymer. It is a polymer which possesses innumerable ester functional groups containing repeating units.
Polyester is formed by the combination of two hydroxyl and two carboxylic group-containing substances.
Polyamide:
Polyamide is another condensation polymer. It is a polymer which possesses innumerable amide functional group-containing repeating units.
It is prepared by the condensation of diamino and carboxylic acid-containing substances and is commonly known as nylon.
Nylon is a thermoplastic polymer and is used in making fishing nets, ropes and in the tyre industry.
Question 5.3:
Write about vulcanised rubber and its uses.
Solution :
Rubber is a naturally occurring polymer obtained from the rubber plant by making a cut in its bark.
Changes can be brought about in this naturally obtained rubber by heating the mixture of rubber and sulphur at 373-413 K. This process is called vulcanisation, and the rubber obtained by this process is called vulcanised rubber. This process was invented by Charles Goodyear.
The reaction of vulcanisation can be speeded up by the addition of zinc oxide.
Properties of vulcanised rubber:
- It has good elasticity.
- It has low water-absorbing property.
- It resists organic solvents and oxidation reactions.
Modifications in vulcanised rubber:
- If 5% of sulphur is added during vulcanisation, rubber suitable for tyres can be manufactured.
- If 30% of rubber is added during vulcanisation, rubber suitable for battery cases can be prepared.
Uses of vulcanised rubber:
- In making rubber bands
- In the manufacture of tubes and tyres of vehicles