MP Board Class 10 Science
Chapter-wise Previous Year Questions & Solutions
Built from the official MPBSE High School question papers — 2021, 2022, 2023, 2024, 2025 and 2026 (Set A)
6 question papers · English version of every question · arranged chapter by chapter
These are the MP Board Class 10 Science previous year questions from the MPBSE High School examination papers of 2021, 2022, 2023, 2024, 2025 and 2026 (Set A), sorted chapter by chapter. The original papers are bilingual (Hindi & English); the English version of every question is reproduced here, along with its marks, its question type and the years it appeared in, followed by a complete step-by-step solution with diagrams and worked numericals.
Chapter 1 · ChemistryChemical Reactions and Equations
34 questions · Years covered: 2021, 2022, 2023, 2024, 2025, 2026
Which type of reaction is the above?
- (a) Combination
- (b) Decomposition
- (c) Displacement
- (d) Double displacement
(b) Decomposition
A single compound (CaCO3) breaks down into two simpler substances. Because heat supplies the energy for the break-up, it is more precisely a thermal decomposition reaction.
This particular reaction is used in the manufacture of quick lime (CaO) from limestone.
The above reaction (shown in the paper) is an example of a:
- (a) Combination reaction
- (b) Double displacement reaction
- (c) Decomposition reaction
- (d) Displacement reaction
Identify the pattern of the equation printed above the options:
| Pattern | Type | Example |
|---|---|---|
| A + B → AB | Combination | CaO + H2O → Ca(OH)2 |
| AB → A + B | Decomposition | CaCO3 → CaO + CO2 |
| A + BC → AC + B | Displacement | Fe + CuSO4 → FeSO4 + Cu |
| AB + CD → AD + CB | Double displacement | Na2SO4 + BaCl2 → BaSO4 + 2NaCl |
Count the reactants and products first: two reactants giving one product is combination; one reactant giving two or more products is decomposition. Then check whether the ions have simply been exchanged, which signals double displacement.
What type of reaction is the reaction of calcium oxide with water?
- (a) endothermic reaction
- (b) exothermic reaction
- (c) neutralization reaction
- (d) redox reaction
(b) Exothermic reaction
CaO(s) + H2O(l) → Ca(OH)2(aq) + heatWhen quick lime reacts with water, a large amount of heat is released — the mixture hisses and the vessel becomes too hot to touch. Any reaction that gives out heat is exothermic.
It is also a combination reaction, since two substances join to give one product. A single reaction can belong to more than one category.
What happens when dilute hydrochloric acid is added to iron filings?
- (a) Hydrogen gas and iron chloride are produced
- (b) Chlorine gas and iron hydroxide are produced
- (c) No reaction takes place
- (d) Iron salt and water are produced
(a) Hydrogen gas and iron chloride are produced
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)Iron is more reactive than hydrogen, so it displaces hydrogen from the acid. This is a displacement reaction. The gas evolved burns with a pop sound when a burning splint is brought near it.
A solution reacts with crushed egg-shells to give a gas that turns lime water milky. The solution contains:
- (a) NaCl
- (b) HCl
- (c) LiCl
- (d) KCl
(b) HCl
Egg shells are made of calcium carbonate. Only an acid will react with a carbonate to release carbon dioxide, and CO2 is the gas that turns lime water milky.
CaCO3 + 2HCl → CaCl2 + H2O + CO2 Ca(OH)2 + CO2 → CaCO3↓ + H2O (milky)The other three options are all neutral salts, which will not react with a carbonate at all.
While cooking food, if the bottom of the vessel is black from outside, then it means that:
- (a) The food is not cooked completely.
- (b) Fuel is not burning completely.
- (c) The fuel is moist.
- (d) Fuel is burning completely.
(b) Fuel is not burning completely
A black deposit on the vessel is unburnt carbon (soot). It forms when the supply of oxygen is insufficient, so the fuel undergoes incomplete combustion and burns with a sooty yellow flame instead of a clean blue one.
The remedy is to clean the air holes of the burner so that enough oxygen reaches the flame.
Energy is absorbed in an exothermic chemical reaction.
False
Energy is released in an exothermic reaction, not absorbed. It is the endothermic reaction that absorbs energy.
| Exothermic | Endothermic |
|---|---|
| Heat is given out; surroundings become warm. | Heat is taken in; surroundings become cool. |
| Burning of natural gas, respiration, quick lime + water. | Decomposition of calcium carbonate, photosynthesis. |
Match: Respiration — with one of: Methyl orange / Exothermic reaction / Insulin / Gold / Mendel / Hydra.
Respiration → Exothermic reaction
C6H12O6 + 6O2 → 6CO2 + 6H2O + energyGlucose is broken down to release energy, and it is this released energy that keeps the body warm. Hence respiration is classed as an exothermic reaction.
What is a combination reaction? / The reactions in which there is an exchange of ions between the reactants are called what?
Combination reaction: a reaction in which two or more substances combine to form a single product.
CaO + H2O → Ca(OH)2Exchange of ions: such reactions are called double displacement reactions.
Na2SO4 + BaCl2 → BaSO4↓ + 2NaClWhy does the colour of copper sulphate solution change when an iron nail is dipped in it? Write the reason and the reaction.
Iron is more reactive than copper, so it displaces copper from copper sulphate solution. The blue copper sulphate is used up and green ferrous sulphate is formed in its place.
Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s) blue green brown depositTwo changes are seen: the solution turns from blue to pale green, and a reddish-brown coating of copper is deposited on the iron nail. This is a displacement reaction.
For whitewashing, which substance solution is used? Write the reaction.
Calcium hydroxide, Ca(OH)2 — commonly called slaked lime — is used for whitewashing walls. It is prepared by adding water to quick lime:
CaO + H2O → Ca(OH)2 + heatAfter the wall has been coated, the slaked lime slowly reacts with the carbon dioxide of the air to form a thin, hard, shiny layer of calcium carbonate:
Ca(OH)2 + CO2 → CaCO3 + H2OThat layer of calcium carbonate is what gives the wall its white, glossy finish, and it takes about two to three days to develop.
Why is respiration considered an exothermic reaction?
Because energy is released during respiration.
The food we eat is digested and broken down into glucose. This glucose then combines with the oxygen taken in by the lungs, inside the cells of the body:
C6H12O6(aq) + 6O2(aq) → 6CO2(aq) + 6H2O(l) + energySince heat energy is given out to the surroundings, and any reaction that gives out heat is called exothermic, respiration is an exothermic reaction. This is also why our body stays warm.
Why should a magnesium ribbon be cleaned before burning in air?
Magnesium is a reactive metal. On being left in air, its surface gets covered with a layer of magnesium oxide (MgO), formed by reaction with the oxygen of the air.
This oxide layer is stable and non-reactive, and it prevents the magnesium underneath from coming into contact with oxygen. So the ribbon will not burn properly.
Rubbing the ribbon with sandpaper removes this coating and exposes the fresh metal, which then burns readily with a dazzling white flame:
2Mg(s) + O2(g) ⟶burn 2MgO(s)Define combination reaction and decomposition reaction.
Combination reaction: a reaction in which two or more substances combine to form a single new substance.
2H2 + O2 → 2H2O CaO + H2O → Ca(OH)2Decomposition reaction: a reaction in which a single compound breaks down into two or more simpler substances. The energy needed may be supplied as heat, light or electricity, and the reaction is named accordingly.
| Type | Example |
|---|---|
| Thermal decomposition | CaCO3 ⟶heat CaO + CO2 |
| Photo-decomposition | 2AgCl ⟶light 2Ag + Cl2 |
| Electrolytic decomposition | 2H2O ⟶electricity 2H2 + O2 |
Decomposition reactions are the opposite of combination reactions, and they are generally endothermic because energy must be supplied to break the compound apart.
What is a precipitation reaction? Write an example.
A reaction in which an insoluble solid, called a precipitate, is formed when two solutions are mixed is called a precipitation reaction. The precipitate separates out and can be seen settling at the bottom.
Example: when sodium sulphate solution is mixed with barium chloride solution, a white precipitate of barium sulphate appears at once.
Na2SO4(aq) + BaCl2(aq) → BaSO4↓(s) + 2NaCl(aq) white precipitateEvery precipitation reaction is also a double displacement reaction, because the ions of the two reactants simply exchange partners.
- (i) When sodium sulphate reacts with barium chloride, what is the name of this type of reaction? Write its chemical equation.
- (ii) Which type of product is produced when calcium oxide reacts with water? Write its chemical reaction.
(i) It is a double displacement reaction — and since an insoluble white solid is formed, it is also a precipitation reaction.
Na2SO4(aq) + BaCl2(aq) → BaSO4↓(s) + 2NaCl(aq)The sulphate and chloride ions have exchanged their partners.
(ii) Calcium oxide reacts vigorously with water to produce calcium hydroxide (slaked lime), releasing a large amount of heat.
CaO(s) + H2O(l) → Ca(OH)2(aq) + heatThis is a combination reaction and it is exothermic.
Write balanced chemical equations for the following reactions:
- (i) Zinc carbonate → Zinc oxide + Carbon dioxide
- (ii) Magnesium + Hydrochloric acid → Magnesium chloride + Hydrogen
- (iii) Lead + Copper chloride → Lead chloride + Copper
- (iv) Sodium sulphate + Barium chloride → Barium sulphate + Sodium chloride
(i) Already balanced — one Zn, one C and three O on each side.
ZnCO3(s) ⟶heat ZnO(s) + CO2(g)Type: thermal decomposition.
(ii) Magnesium chloride is MgCl2, so two chlorine atoms are needed — put 2 before HCl.
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)Type: displacement.
(iii) Both chlorides are of the form MCl2, so no coefficients are needed.
Pb(s) + CuCl2(aq) → PbCl2(aq) + Cu(s)Type: displacement. Lead is above copper in the reactivity series, so it can displace copper.
(iv) Two sodium and two chlorine atoms are needed on the right — put 2 before NaCl.
Na2SO4(aq) + BaCl2(aq) → BaSO4↓(s) + 2NaCl(aq)Type: double displacement / precipitation.
Transform the following statements into balanced chemical equations:
- (i) Hydrogen gas combines with nitrogen to form ammonia.
- (ii) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
- (iii) Barium chloride reacts with sulphuric acid to give barium sulphate and hydrochloric acid.
- (iv) Hydrogen sulphide gas burns in air to give water and sulphur dioxide.
(i) Ammonia is NH3. Two nitrogen atoms need 2NH3, which needs six hydrogen atoms, i.e. 3H2.
3H2(g) + N2(g) → 2NH3(g)(ii) Balance K first, then H.
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g)(iii) Two chlorine atoms on the left need 2HCl on the right.
BaCl2(aq) + H2SO4(aq) → BaSO4↓(s) + 2HCl(aq)(iv) Take 2H2S to get 2S; that gives 2SO2 and 2H2O, needing 2 + 4 = 6 oxygen atoms, i.e. 3O2.
2H2S(g) + 3O2(g) → 2H2O(l) + 2SO2(g)Method to remember: balance metals first, then non-metals, then hydrogen, and oxygen last. Never change a formula to balance an equation — only put numbers in front of it.
What do you mean by oxidation–reduction (redox) reactions? Explain with an example. What do you mean by exothermic and endothermic reactions? Explain with examples.
Oxidation is the gain of oxygen or the loss of hydrogen by a substance. Reduction is the loss of oxygen or the gain of hydrogen.
In every reaction where one substance is oxidised, another is simultaneously reduced. Such a reaction is called a redox reaction — the word is short for reduction–oxidation.
Example:
CuO + H2 ⟶heat Cu + H2O- CuO loses oxygen to become Cu — copper oxide is reduced.
- H2 gains oxygen to become H2O — hydrogen is oxidised.
Both happen in the same reaction, so it is a redox reaction.
Exothermic reaction: one in which heat is released along with the products, so the surroundings become warmer.
CH4 + 2O2 → CO2 + 2H2O + heatOther examples: respiration, the burning of coal or natural gas, and the slaking of quick lime.
Endothermic reaction: one in which heat is absorbed from the surroundings, which therefore become cooler.
CaCO3 ⟶heat CaO + CO2Other examples: photosynthesis, and the decomposition of ferrous sulphate on heating.
Chapter 2 · ChemistryAcids, Bases and Salts
21 questions · Years covered: 2021, 2022, 2023, 2024, 2025, 2026
A solution turns blue litmus to red. Its pH is likely to be:
- (a) 1
- (b) 7
- (c) 10
- (d) 14
(a) 1
Only an acid turns blue litmus red, and acids have a pH less than 7. Of the options given, only 1 lies below 7.
| pH range | Nature | Effect on litmus |
|---|---|---|
| 0 – 7 (less than 7) | Acidic | Blue litmus → red |
| Exactly 7 | Neutral | No change |
| 7 – 14 (more than 7) | Basic | Red litmus → blue |
The smaller the pH, the greater the concentration of H+ ions and the stronger the acid.
Which of the following is an example of an amphoteric oxide?
- (a) Na2O
- (b) Al2O3
- (c) CO2
- (d) MgO
(b) Al2O3
An amphoteric oxide reacts with both acids and bases to give salt and water. Aluminium oxide and zinc oxide are the two standard examples.
Al2O3 + 6HCl → 2AlCl3 + 3H2O (acts as a base) Al2O3 + 2NaOH → 2NaAlO2 + H2O (acts as an acid)Na2O and MgO are basic oxides; CO2 is an acidic oxide.
Which one of the following types of medicines is used for treating indigestion?
- (a) Antibiotic
- (b) Analgesic
- (c) Antacid
- (d) Antiseptic
(c) Antacid
Indigestion and acidity are caused by the stomach producing too much hydrochloric acid. An antacid is a mild base — such as milk of magnesia, Mg(OH)2, or baking soda — which neutralises the excess acid and relieves the pain.
Antibiotics kill bacteria, analgesics relieve pain, and antiseptics are applied to wounds to stop infection.
__________ acid is present in vinegar.
Acetic acid (ethanoic acid, CH3COOH). Vinegar is a 5–8% solution of acetic acid in water.
| Source | Acid present |
|---|---|
| Vinegar | Acetic acid |
| Citrus fruits (orange, lemon) | Citric acid |
| Curd | Lactic acid |
| Ant sting / nettle sting | Methanoic (formic) acid |
| Tamarind | Tartaric acid |
| Tomato | Oxalic acid |
Match the following pairs asked across three years:
- (i) Strong acid — ?
- (ii) Synthetic indicator — ?
- (iii) Orange — ?
- (iv) Ant sting — ?
- (v) Vinegar — ?
- (vi) Marble — ?
| Item | Match |
|---|---|
| Strong acid | HCl |
| Synthetic indicator | Methyl orange |
| Orange | Citric acid |
| Ant sting | Methanoic acid |
| Vinegar | Acetic acid |
| Marble | CaCO3 |
Indicators are of three kinds — natural (litmus, red cabbage, turmeric), synthetic (methyl orange, phenolphthalein) and olfactory (onion, vanilla essence, which change in smell rather than colour).
What is the pH scale? Write the pH value of pure water.
The pH scale is a scale for measuring the concentration of hydrogen ions in a solution, and hence how acidic or basic it is. It runs from 0 to 14.
The pH of pure water is 7, which is exactly neutral — it is neither acidic nor basic.
The 'p' in pH stands for potenz, the German word for…