In CBSE Class 10 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.
Here, we have provided case based/passage based questions for Class 10 Science Chapter 1 Chemical Reactions and Equations.
Case Study/Passage Based Questions
Corrosion is the phenomenon of deterioration of surface of metal in presence of air and moisture. It is a natural process and in the presence of a moist atmosphere, chemically active metals get corroded. This is an oxidation reaction. Rusting is the process where iron corrodes due to exposure to the atmosphere. The main circumstance of corrosion occurs with iron because it is a structural material in construction, bridges, buildings, rail transport, ships, etc. Aluminium is also an important structural metal, but even aluminium undergoes oxidation reactions. However, aluminium doesn’t corrode or oxidize as rapidly as its reactivity suggests. Copper (Cu) corrodes and forms a basic green carbonate.
(i) What is rusting?
AnswerAnswer: The deterioration of surface of iron in presence of air and moisture is called rusting.
(ii) Which two metals do not corrode easily?
AnswerAnswer: Gold and Platinum
(iii) Write the chemical name of the compound formed on corrosion of silver.
AnswerAnswer: Silver sulphide, Ag2S
(iv) Corrosion is
(a) a redox reaction
(b) a reduction reaction
(c) a displacement reaction
(d) an oxidation reaction
Oxidation is the process of gaining of oxygen, or losing of hydrogen. Reduction is the process of losing of oxygen or gaining of hydrogen. The substance which undergoes oxidation is the reducing agent while the substance which undergoes reduction is known as the oxidising agent. Oxidation and reduction always take place together and these type of reactions are known as redox reactions. Some of the examples of redox reactions are given below:
(i) Give two examples of oxidation reaction from your everyday life.
AnswerAnswer: Corrosion and Rancidity
(ii) Write the oxidising agent in the reaction III and VI.
AnswerAnswer: CuSO4 in (III) and CuO in (VI)
(iii) Which of the following is an oxidising agent?
(b) Alkaline KMnO4
(c) Acidified K2Cr2O7
(d) Both (b) and (c)
(iv) Out of oxidation and reduction, which reaction takes place at anode?
AnswerAnswer: Oxidation takes place at anode.
A chemical reaction is a representation of chemical change in terms of symbols and formulae of reactants and products. There are various types of chemical reactions like combination, decomposition, displacement, double displacement, oxidation and reduction reactions. Reactions in which heat is released along with the formation of products are called exothermic chemical reactions. All combustion reactions are exothermic reactions.
(i) The chemical reaction in which a single substance breaks down into two or more simpler substances upon heating is known as
(a) thermal decomposition reaction
(b) photo decomposition reaction
(c) electric decomposition reaction
(d) both (a) and (c)
AnswerAnswer: (a) The chemical reaction in which a single substance breaks down into two or more simpler substances upon heating is known as thermal decomposition reaction.
(ii) The massive force that pushes the rocket forward through space is generated due to the
(a) combination reaction
(b) decomposition reaction
(c) displacement reaction
(d) double displacement reaction
AnswerAnswer: (b) The massive force that pushes the rocket forward through space is generated due to the decomposition reaction. Hydrogen peroxide decomposes and provides it with a considerable reaction force thrust.
(iii) A white salt on heating decomposes to give brown fumes and yellow residue is left behind. The yellow residue left is of
(a) lead nitrate
(b) nitrogen oxide
(c) lead oxide
(d) oxygen gas
AnswerAnswer: (c) Lead nitrate decomposes to give brown fumes of nitrogen dioxide gas and yellow residue of lead oxide is left behind.
(iv) Which of the following reactions represents a combination reaction?
(a) CaO (s) + H2O (l) → Ca(OH)2 (aq)
(b) CaCO3 (s) → CaO (s) + CO2(g)
(c) Zn(s) + CuSO4 (aq) → ZnSO4 (aq) + Cu(s)
(d) 2FeSO4(s) → Fe2O3 (s) +SO2(g) + SO3(g)
AnswerAnswer: (a) A reaction in which two or more reactants combine to form a single product is known as a combination reaction.
(v) Complete the following statements by choosing correct type of reaction for X and Y.
Statement 1: The heating of lead nitrate is an example of ‘X’ reaction.
Statement 2: The burning of magnesium is an example of ‘Y’ reaction.
(a) X- Combination, Y- Decomposition
(b) X- Decomposition, Y-Combination
(c) X- Combination, Y-Displacement
(d) X- Displacement, Y-Decomposition