Practice Top Chemical Reaction and Equation Class 10 MCQs for 2025-26 Exams
FAQs on Master Class 10 Science: Chemical Reaction and Equation MCQs with Expert Answers
1. What are the most important topics from Chapter 1, Chemical Reactions and Equations, for the Class 10 Board Exam 2025-26?
For the CBSE Class 10 Board Exam, the most important topics from this chapter are:
Balancing chemical equations, as it is a fundamental skill tested frequently.
Identifying the types of chemical reactions, especially combination, decomposition, displacement, and double displacement, with one example for each.
Understanding oxidation and reduction (redox reactions) with clear examples.
Application-based questions on the effects of oxidation in daily life, such as corrosion and rancidity.
2. What format of questions can be expected from this chapter in the board exams?
From Chapter 1, you can expect a mix of question formats aligned with the CBSE pattern. These typically include:
Multiple Choice Questions (MCQs) testing basic definitions and identification of reaction types.
Very Short Answer (VSA) questions (2 marks) asking to define a term or balance a simple equation.
Short Answer (SA) questions (3 marks) which might involve identifying reaction types from given equations or explaining concepts like rancidity.
Long Answer (LA) questions (5 marks), often asking to define multiple reaction types with examples or involving a detailed explanation of a redox reaction.
3. What is a crucial tip for balancing chemical equations to score full marks in the exam?
To ensure you score full marks, always use the hit-and-trial method systematically. Start by balancing the element that appears in the fewest compounds. After balancing, perform a final check by counting the atoms of each element on both the reactant and product sides. Crucially, always remember to write the physical states (s, l, g, aq) of reactants and products, as marks are often allotted for this detail.
4. Are questions on corrosion and rancidity important for the Class 10 exam?
Yes, questions on corrosion and rancidity are very important as per recent board trends. They are often asked as application-based or conceptual questions for 2 or 3 marks. Be prepared to explain the chemical processes involved, provide real-life examples like the rusting of iron, and suggest methods of prevention, such as painting or storing food in airtight containers.
5. How can a student differentiate between displacement and double displacement reactions during an exam?
The key difference to look for in an exam is the number of components being exchanged.
In a displacement reaction, a more reactive element displaces a less reactive element from its compound. Only one element is displaced. Example: Fe + CuSO₄ → FeSO₄ + Cu.
In a double displacement reaction, there is an exchange of ions between two aqueous compounds to form two new compounds. It often results in the formation of a precipitate. Example: Na₂SO₄(aq) + BaCl₂(aq) → BaSO₄(s) + 2NaCl(aq).
6. Why is balancing a chemical equation a frequently asked question?
Balancing a chemical equation is a fundamental concept frequently tested because it directly relates to the Law of Conservation of Mass. This law states that mass can neither be created nor destroyed in a chemical reaction. An unbalanced equation violates this core scientific principle. Examiners test this to check a student's deep understanding, not just their ability to manipulate numbers.
7. Can a reaction be both a redox reaction and another type, like combination? What kind of HOTS question can be framed on this?
Yes, a single reaction can be classified in multiple ways. For instance, the burning of magnesium in air (2Mg + O₂ → 2MgO) is a combination reaction because two substances combine to form one. It is also a redox reaction because magnesium is oxidised (loses electrons) and oxygen is reduced (gains electrons). A typical Higher Order Thinking Skills (HOTS) question might ask you to 'Justify with an example that a combination reaction can also be a redox reaction.'
8. Besides definitions, how are questions on decomposition reactions typically asked for higher marks?
For higher marks (3 or 5 marks), questions on decomposition reactions often focus on the different forms of energy required to break down the reactant. You may be asked to:
Provide one example each for thermal decomposition (using heat), electrolytic decomposition (using electricity), and photolytic decomposition (using light).
Write the balanced chemical equations for each.
Mention an important application, such as the use of photolytic decomposition in black and white photography.
9. What is a common mistake students make when identifying precipitation reactions?
A common mistake is failing to correctly identify the insoluble product, which is the precipitate. A precipitation reaction is a specific type of double displacement reaction where one of the products formed is insoluble. To get full marks, you must write the balanced equation and clearly indicate the precipitate with the state symbol (s). For example, in the reaction AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq), identifying silver chloride (AgCl) as the solid precipitate is crucial.
