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CBSE · Class 10 · Science

Acids, Bases and Salts

Standard difficulty · 20 questions · 40 marks

Name: Date: Score: ____ / 40

Show your working for Sections B and C. Answers are on the last page — try every question first!

Section A — Choose the correct answer8 × 1 = 8 marks
1.
What colour is phenolphthalein in dilute sulphuric acid?
  1. colourless
  2. red
  3. green
  4. reddish-brown
2.
Solutions P, Q, R and S have pH values of 13, 10, 9, 8 respectively. Which has the highest concentration of hydrogen ions?
  1. P
  2. Q
  3. S
  4. R
3.
Acids turn blue litmus:
  1. green
  2. blue
  3. colourless
  4. red
4.
Nitric acid reacts with potassium hydroxide. The salt formed is:
  1. KNO3
  2. K2SO4
  3. K2CO3
  4. KCl
5.
The chemical formula of common salt is:
  1. CuSO4·5H2O
  2. NaOH
  3. Ca(OH)2
  4. NaCl
6.
Which of these salts gives an acidic solution in water?
  1. potassium chloride (KCl)
  2. sodium hydrogencarbonate (NaHCO3)
  3. zinc sulphate (ZnSO4)
  4. sodium ethanoate (CH3COONa)
7.
How many molecules of water of crystallisation are there in one formula unit of blue vitriol (copper sulphate crystals)?
  1. 10
  2. 2
  3. 5
  4. 1
8.
Assertion (A): A solution with a pH of 10 is acidic.
Reason (R): A pH below 7 means a solution is acidic, and a pH above 7 means it is basic.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
Section B — Short answer8 × 2 = 16 marks
9.
Write the balanced equation for the reaction of nitric acid with potassium hydroxide. Name the salt formed.
10.
Write the balanced equation for the reaction of calcium oxide (CaO) with dilute sulphuric acid. Name the products.
11.
Zinc carbonate reacts with dilute nitric acid. Name the gas given off and write the balanced equation.
12.
Why should water never be added to a concentrated acid?
13.
528.2 g of ferrous sulphate crystals (FeSO4·7H2O) is heated until all its water of crystallisation is lost. Find the mass of water lost and the mass of the anhydrous salt left. (Atomic masses: H = 1 u, O = 16 u, S = 32 u, Fe = 56 u)
14.
Solutions P, Q, R and S have pH values of 8, 9, 13, 1 respectively. Arrange them in increasing order of hydrogen-ion concentration. Which of them are acidic?
15.
Will a solution of ammonium sulphate ((NH4)2SO4) be acidic, basic or neutral? Give a reason.
16.
Give the chemical name and formula of Epsom salt, and one use.
Section C — Word problems4 × 4 = 16 marks
17.
What is the chlor-alkali process? Write the equation and give one use of each product.
18.
68 g of sodium hydroxide is exactly neutralised by hydrochloric acid. Write the balanced equation and find the mass of acid needed and the mass of salt formed. (Atomic masses: H = 1 u, O = 16 u, Na = 23 u, Cl = 35.5 u)
19.
Three test tubes contain sodium chloride solution, dilute sulphuric acid, potassium hydroxide solution. For each, give the colour of (i) blue litmus, (ii) phenolphthalein and (iii) methyl orange, and say whether it is acidic, basic or neutral.
20.
Write balanced equations to prepare zinc sulphate from (a) the metal and (b) its hydroxide, each with dilute sulphuric acid.
AmbifulWorksheets
Practice that never repeats
CBSE · Class 10 · Science

Answer key

Acids, Bases and Salts · AW-10S-ABS-2026-V1 · For parents — fold back or tear off before handing the sheet to your child.

QAnswerWorking
1(a) colourlessdilute sulphuric acid is acidic
2(c) Sthe lowest pH is the most acidic (most H+ ions)
3(d) red—
4(a) KNO3HNO3 + KOH → KNO3 + H2O
5(d) NaCl—
6(c) zinc sulphate (ZnSO4)zinc sulphate comes from a strong acid and a weak base
7(c) 5—
8(d) A is false, but R is true.A is false: pH 10 is above 7, so the solution is basic. R is true.
9HNO3 + KOH → KNO3 + H2O; potassium nitrateacid + base → salt + water
10CaO + H2SO4 → CaSO4 + H2O; calcium sulphate and watermetal oxide + acid → salt + water
11Carbon dioxide; ZnCO3 + 2HNO3 → Zn(NO3)2 + H2O + CO2carbonate + acid → salt + water + carbon dioxide
12Mixing gives out a lot of heat; adding water to the acid can make it boil and splash out. Always add acid slowly to water.—
13239.4 g of water; 288.8 g of FeSO4FeSO4·7H2O = 278 u, of which water is 126 u
14R < Q < P < S; acidic: Sthe lower the pH, the more H+ ions
15Acidic: it comes from a strong acid (sulphuric acid) and a weak base (ammonium hydroxide).—
16Magnesium sulphate heptahydrate, MgSO4·7H2O; used in bath salts and as a laxative—
17The electrolysis of brine (sodium chloride solution): 2NaCl + 2H2O → 2NaOH + Cl2 + H2. Sodium hydroxide: soaps, detergents, paper. Chlorine: disinfecting water, PVC, bleaching powder. Hydrogen: fuels, margarine, ammonia.—
18NaOH + HCl → NaCl + H2O; 62.05 g of HCl; 99.45 g of NaCl1.7 mol of NaOH; use the ratio 1 : 1 : 1 : 1
19sodium chloride solution: blue, colourless, orange (neutral); dilute sulphuric acid: red, colourless, red (acidic); potassium hydroxide solution: blue, pink, yellow (basic)—
20(a) Zn + H2SO4 → ZnSO4 + H2; (b) Zn(OH)2 + H2SO4 → ZnSO4 + 2H2O—