Vidaara.orgClass 10 · Chemistry
CodeVID-C10-02-T1-01
Acids, Bases & their Reactions — Assignment
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.
- Write balanced chemical equations wherever asked and show all working.
Section A — Multiple Choice Questions
5 × 1 = 5 marks
1.
Which ion is responsible for the acidic nature of a solution?
- A.OH⁻
- B.H⁺
- C.Cl⁻
- D.CO₃²⁻
2.
Acid + metal carbonate gives salt, water and:
- A.hydrogen
- B.oxygen
- C.carbon dioxide
- D.ammonia
3.
The reaction NaOH + HCl → NaCl + H2O is called:
- A.displacement
- B.neutralisation
- C.decomposition
- D.combination
4.
A non-metal oxide is generally:
- A.acidic
- B.basic
- C.neutral
- D.amphoteric
5.
While diluting an acid, the correct practice is to add:
- A.water to acid quickly
- B.acid to water slowly
- C.acid and water together
- D.ice to acid
Section B — Short Answer (2 marks)
3 × 2 = 6 marks
6.
Write the balanced equation for the reaction of magnesium with dilute hydrochloric acid.
7.
Why does dry HCl gas not turn blue litmus red?
8.
State why acids should always be added to water and not water to acid.
Section C — Short Answer (3 marks)
2 × 3 = 6 marks
9.
Describe the reaction of dilute sulphuric acid with sodium hydrogencarbonate, giving the balanced equation and the test for the gas evolved.
10.
Explain, with a conductivity test, how you can show that it is the ions in an acid that conduct electricity.
Section D — Long Answer (5 marks)
1 × 5 = 5 marks
11.
Describe the chemical reactions of acids with (a) metals, (b) metal carbonates, (c) bases and (d) metal oxides, giving one balanced equation for each.
Answer Key
Section A — Multiple Choice Questions
- (B) H⁺
- (C) carbon dioxide
- (B) neutralisation
- (A) acidic
- (B) acid to water slowly
Section B — Short Answer (2 marks)
- Mg + 2HCl gives MgCl2 + H2; hydrogen gas is evolved.
- Acidic character needs free H+ ions, which form only in water; dry HCl does not ionise, so it has no H+ ions and cannot turn litmus red.
- The dilution is highly exothermic; adding water to acid makes the mixture boil and splash, so acid is added slowly to water to release heat safely.
Section C — Short Answer (3 marks)
- 2NaHCO3 + H2SO4 gives Na2SO4 + 2H2O + 2CO2. The gas is carbon dioxide; on passing it through lime water, the lime water turns milky.
- Set up a beaker of dilute HCl with two electrodes connected to a bulb and a battery; the bulb glows because H+ and Cl- ions carry the current. A glucose solution in the same setup gives no glow because it has no ions, proving ions are responsible for conduction.
Section D — Long Answer (5 marks)
- (a) Metals: Zn + 2HCl gives ZnCl2 + H2 (salt + hydrogen). (b) Metal carbonates: Na2CO3 + 2HCl gives 2NaCl + H2O + CO2 (salt + water + carbon dioxide). (c) Bases (neutralisation): NaOH + HCl gives NaCl + H2O (salt + water). (d) Metal oxides (basic, so they neutralise acids): CuO + 2HCl gives CuCl2 + H2O, forming a blue-green solution. In every case a salt is formed; the second product differs with the reactant.
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