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When a small piece of sodium is dropped into ethanol it releases hydrogen gas and forms sodium ethoxide.

2C₂ H₅ OH + 2 Na → 2C₂ H₅ ONa + H₂

(a) Functional group is an atom or group of atoms or reactive part of compound, which determines chemical properties of compounds. 

(i) —OH (Alcohol) 

(ii) —COOH (Carboxylic acid)

(a) Carbon forms large number of compounds since carbon is small in size and can form stable covalent bonds (catenation) and it shows tetravalency. 

(b) Air holes of gas burner are made open (adjusted) so that air can pass through, which is needed for complete combustion, so that heated vessels do not get blackened. 

(c) Some synthetic detergents are non-biodegradable, therefore, cause pollution of water

(a) 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.

Example of Homologous series: All the alkanes have similar structures with single covalent bonds and show similar chemical properties, so they can be grouped together in the form of a homologous series. Homologous series of alkanes: Methane, CH₄ ; Ethane, C₂H₆ ; Propane, C₃H₈ ; Butane, C₄H₁₀ ; Pentane, C₅H₁₂ 

(b) (i) All the members of the homologous series can be represented by the same general formula.

(ii) Any two adjacent homologues differ by 1 carbon atom and 2 hydrogen atoms in their molecular formulae.

(c) Alkene, C_nH_2n 

(d) In an organic compound, any atom other than carbon and hydrogen is called a heteroatom. Example: Chlorine (Cl), Bromine (Br), Oxygen (O) Chloromethane – CH₃Cl and methanol – CH₃OH

(a) C₅H₁₂O or C₅H₁₁OH

(b) When a candle is lighted, the wax melts, rises up the wick and gets converted into vapours. In a candle, there is no provision for the proper mixing of oxygen (of air) for burning wax vapours. So, the wax vapours bum in an insufficient supply of oxygen (of air) which leads to incomplete combustion of wax. This incomplete combustion of wax produces small unburnt carbon particles. These solid carbon particles rise in the flame, get heated and glow to give out yellowish light. This makes the candle flame yellow and luminous.

The compound is Propanone.

Take two test tubes, add ethanol and ethanoic acid in test tube A and B respectively. Add sodium carbonate/sodium hydrogen carbonate solution in both the test tubes, the test tube which will produce brisk effervescence of CO₂ gas will contain ethanoic acid. Ethanol do not evolve CO₂ gas when reacted with Na₂CO₃/ NaHCO₃.

Differences between Soaps and Detergents

Disadvantages of Detergents

Detergents are surface-active agents and cause a variety of water pollution problems.

• Many detergents are resistant to the action of biological agents and thus are not biodegradable. Their elimination from municipal wastewaters by the usual treatments is a problem.

• They have a tendency to produce stable foams in rivers that extend over several hundred meters of the river water. This is due to the effects of surfactants used in their preparation. Thus they pose a danger to aquatic life.

• They tend to inhibit oxidation of organic substances present in wastewaters because they form a sort of envelope around them.

Disadvantages of incomplete combustion: 

(i) It leads to the formation of soot which is nothing but unburnt carbon which pollutes the atmosphere, blackens cooking utensils. 

(ii) It leads to the formation of an extremely poisonous gas called carbon monoxide.

(i) Propanone

(ii) Butanone

C — Ethanoic acid

R — Sodium salt of ethanoic acid (sodium acetate) and gas evolved is hydrogen 

A — Methanol 

S — Ester (Methyl acetete) 

(a) 2CH₃COOH + 2Na → 2CH₃COO Na + H₂

 (b) \(CH_3COOH+NaOH\overset{Conc.H_2SO_4}\rightarrow CH_3COOCH_3+H_2O\)

(c) CH₃COOH + NaOH → CH₃COONa + H₂O

(d) CH₃COOCH₃ + NaOH → CH₃COONa + CH₃OHa

The compounds that contain the same molecular formula but different structures are called isomers. The isomers of a compound have different physical properties

By saponification reaction, by adding/reacting ester with NaOH.

(i) Chemically, vinegar is 5-8% of the acetic acid solution in water.

Formula: CH₃COOH.

(ii) When ethanol reacts with sodium, it gives sodium ethoxide and hydrogen gas.

CH₂CH₂OH+Na → CH₃CH₂ONa+H₂↑

CH₂CH₂OH-Ethanol

Na-Sodium metal

CH₃CH₂ONa-Sodium ethoxide

H₂  -Hydrogen gas.

(i) Aldehyde, (ii) Carboxylic acid.

(i) High melting point and high boiling point. 

(ii) Can conduct electricity

The compound is 2-Butanone.

Pass the vapours of the given samples of saturated and unsaturated hydrocarbons into bromine water taken in two separate test-tubes. The one which discharges the colour of bromine water is that of unsaturated hydrocarbon and the other represents saturated hydrocarbon.

1. Electronic configuration of carbon is 1s²2s²2p². 

2. If carbon loses four electrons from the outer shell, it will form C⁴⁺ ions. 

3. This requires huge amount of energy which is not available normally. 

4. Therefore C⁴⁺ formation is not possible.

Diamond has a rigid 3D structure in which each carbon atom is covalently bonded to 4 other carbon atoms. This structure involves a network of strong C-C bonds which requires high energy to break the bonds. Hence, the diamond has a high melting point.

(i) C is a covalent compound, as the combining atoms form a bond by sharing of electrons.

(ii) Using “like dissolves like” rule, polar molecules dissolve in polar solvents, whereas non-polar molecules dissolve in non-polar solvents. C and organic solvents are both covalent (non-polar) in nature, but water is a polar solvent. Hence C will dissolve in organic solvents.

The molecular formula of ethene is C₂H₄. The three succeeding members in this homologous series are: 

Propene (C₃H₆), Butene (C₄H₈), Pentene (C₅H₁₀)

Correct option is  D) C₄H₁₀

(i) Carbon has the ability to form long, branched chains or ring structures with other carbon atoms. This self-linking capacity is referred to as catenation. Also carbon has a valency of 4 and combines with 4 other monovalent atoms or shares its outermost electrons with different elements through single, double or triple bonds. The bonds formed are highly strong and stable. Hence carbon forms a large variety of compounds. 

(ii) 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 the carbon atoms are called unsaturated compounds. 

(iii) Unsaturated compounds are more reactive than saturated compounds because of the presence of double or triple bonds present in them. These bonds tend to break in the presence of some reacting species to become saturated compounds which are highly stable. The relative stability of hydrocarbons in the decreasing order is given by: 

alkanes > alkenes > alkynes

The answer is (d) (ii) and (iv)

• Carbon compounds form covalent bonds hence they have very weak force of attraction. 
• Carbon compounds are poor conductors of electricity.

(i) Saturated hydrocarbons undergo substitution reaction through a mechanism called “free radical mechanism”, where the initial step of reaction is the formation of free radicals. Generation of free radicals requires sunlight, without which the reaction does not get initiated. So, sunlight is necessary for the substitution reactions of saturated hydrocarbons. 

(ii) Ethyne (HC≡CH) is an unsaturated compound, and unsaturated compounds produce yellow sooty flame with lots of black smokes. This is due to incomplete combustion of ethyne in air.

Low reactivity.

Hydrocarbons – Compounds containing carbon and hydrogen.

Organic Compounds – Hydrocarbons and compounds derived from hydrocarbons.

Tetravalency in Carbon

A carbon atom has a total of six electrons occupying the first two shells, i.e., the K-shell has two electrons and the L-shell has four electrons. This distribution indicates that in the outermost shell there are one completely filled 's' orbital and two half-filled 'p' orbitals, showing carbon to be a divalent atom. But in actuality, carbon displays tetravalency in the combined state. Therefore, a carbon atom has four valence electrons. It could gain four electrons to form C^4- anion or lose four electrons to form C⁴⁺ cation. Both these conditions would take carbon far away from achieving stability by the octect rule. To overcome this problem carbon undergoes bonding by sharing its valence electrons. This allows it to be covalently bonded to one, two, three or four carbon atoms or atoms of other elements or groups of atoms.

Correct option is  C) 3

The answer is (a) only single bonds

• Nitrogen has three electron in its outermost shell and hydrogen has 1. 
• 3 hydrogen atoms combine with 1 nitrogen atom to make ammonia. 
• These bonds are single bonds.

Detergents are cleansing agents which are ammonium or sulphonate salts of long chain carboxylic acids.

Synthetic detergents which consist of continuous chains of carbon are more biodegradable when compared to the branched-chain synthetic detergents.

(A) only single bonds

Carbon generally forms compounds by, covalent bonds because carbon can neither donate nor accept four electrons for completing its octet. So, it shares its four electrons with other atoms forming covalent bonds.

In column chromatography, its given that compound Y is eluted in preference to compound X. That means the compound X is adsorbed more than the compound Y. Because less adsorbed compound comes out first.  

Gandhiji promised to send him a cup of light coffee and warm toast.

The boy imagined that Gandhiji would go to Ba in her kitchen and ask for coffee and toast for him.

Gandhiji himself made the coffee because it was an untimely hour and he did not like to rouble Ba as she would be taking rest.

The word brain-wave means a thought in mind that appears suddenly.

The young lad liked the coffee much because he was habitual to take it.

Correct option is (c) a long way across the road at the other end of the Ashram

The young lad requested Gandhiji for a cup of coffee.

When the young lad saw Gandhiji carrying a tray covered with a white khadi napkin, he was surprised.

Correct option is (b) warm toast and coffee