Vidaara.orgClass 10 · Chemistry
CodeVID-C10-04-T3-01
Assignment — Chemical Properties & Important Carbon Compounds
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
- Show all working for Sections B, C and D. Only final answers are given at the end — for full solutions, raise your doubts with your teacher.
Section A — Multiple Choice Questions
5 × 1 = 5 marks
1.
Conversion of ethanol to ethanoic acid is an example of:
- A.reduction
- B.oxidation
- C.substitution
- D.addition
2.
The catalyst used in hydrogenation of oils is:
- A.platinum
- B.iron
- C.nickel
- D.copper
3.
Vinegar is a dilute aqueous solution of:
- A.ethanol
- B.ethanoic acid
- C.methanol
- D.ethyl ethanoate
4.
The water-hating part of a soap molecule is the:
- A.ionic head
- B.hydrocarbon tail
- C.sodium ion
- D.carboxylate group
5.
The reaction CH4 + Cl2 → CH3Cl + HCl (in sunlight) is a:
- A.addition reaction
- B.substitution reaction
- C.combustion reaction
- D.oxidation reaction
Section B — Short Answer (2 marks)
3 × 2 = 6 marks
6.
Write the equation for the reaction of ethanol with sodium.
7.
What is a substitution reaction? Give one example.
8.
Why does ethanoic acid release a gas with sodium carbonate? Name the gas.
Section C — Short Answer (3 marks)
2 × 3 = 6 marks
9.
Explain the cleansing action of soap with the help of the idea of a micelle.
10.
Write the equation for esterification of ethanoic acid with ethanol and state two uses of esters.
Section D — Long Answer (5 marks)
1 × 5 = 5 marks
11.
Describe the important chemical properties of ethanoic acid: its reaction with a base, with a carbonate, and with an alcohol (esterification). Write balanced equations for each and explain why soaps fail in hard water while detergents do not.
Answer Key
Section A — Multiple Choice Questions
- (B) oxidation
- (C) nickel
- (B) ethanoic acid
- (B) hydrocarbon tail
- (B) substitution reaction
Section B — Short Answer (2 marks)
- 2C2H5OH + 2Na -> 2C2H5ONa + H2 (sodium ethoxide and hydrogen gas are formed).
- A substitution reaction is one in which an atom or group replaces another, e.g. CH4 + Cl2 -> CH3Cl + HCl in the presence of sunlight.
- Ethanoic acid is an acid and reacts with carbonates to give carbon dioxide gas: 2CH3COOH + Na2CO3 -> 2CH3COONa + H2O + CO2. The gas is carbon dioxide.
Section C — Short Answer (3 marks)
- Soap molecules have a hydrophobic tail and a hydrophilic head. In water they form micelles with the tails pointing inward (into the oily dirt) and the heads outward (into the water). The oil is trapped inside the micelle and washed away with rinse water, so the cloth is cleaned.
- CH3COOH + C2H5OH -> CH3COOC2H5 + H2O (with conc. H2SO4 as catalyst). Esters are sweet-smelling and are used in perfumes and as flavouring agents in food.
Section D — Long Answer (5 marks)
- Ethanoic acid reacts with a base: CH3COOH + NaOH -> CH3COONa + H2O (neutralisation giving sodium ethanoate and water). With a carbonate: 2CH3COOH + Na2CO3 -> 2CH3COONa + H2O + CO2 (carbon dioxide is released, turning lime water milky). Esterification with an alcohol: CH3COOH + C2H5OH -> CH3COOC2H5 + H2O (conc. H2SO4 catalyst), giving a sweet-smelling ester. Soaps fail in hard water because the Ca2+ and Mg2+ ions present react with the soap to form an insoluble scum, wasting it; detergents form soluble calcium and magnesium salts, so they do not produce scum and clean effectively even in hard water.
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