CBSE Class 10 - Chemistry - Acids, Bases and Salts - Assertion Reason Based Questions
Assertion and Reasoning based questions are a bit tricky. You should be able to distinguish whether the assertion is well connected to the reason or these are just random facts. Read both statements carefully, and check if both statements are factually or logically correct or not. If both are correct, then try to check if both are well connected to each other or not.
The questions below consist of statements of an Assertion and a Reason. Use the following key to choose an appropriate answer:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Q1: Assertion (A) : Acids are those substances which turn blue litmus solution red.
Reason (R) : Acids give more OH⁻ ions in aqueous solution.
Q2: Assertion (A) : The aqueous solutions of glucose and alcohol do not show acidic character.
Reason (R) : Aqueous solutions of glucose and alcohol do not give H⁺ ions.
Q3: Assertion (A) : Litmus solution is a natural acid-base indicator.
Reason (R) : It is a purple dye which is extracted from a plant ‘lichen’.
Q4: Assertion (A) : The acid must always be added to water with constant stirring.
Reason (R) : Mixing of an acid with water decreases the concentration of H⁺ ions per unit volume.
Q5: Assertion (A) : Curd and Sour Substances should be kept in brass and copper vessels
Reason (R) : They are mild acids and react with brass and copper to produce toxic substances.
Q6: Assertion (A) : Weak acids have low electrical conductivity.
Reason (R) : Strong acids and weak acids have equal concentration of hydrogen ions in their solutions.
Q7: A white coloured powder is used by the doctors for supporting fractured bones.
Assertion (A) : It is plaster of Paris
Reason (R) : It is also called gypsum.
Q8: Assertion (A) : Pure water is neither acidic nor basic.
Reason (R) : The pH of a solution is inversely proportional to the concentration of hydrogen ions in it.
Q9: Assertion (A) : Tooth decay starts when pH of mouth is lower than 5.5.
Reason (R) : Tooth enamel made up of calcium phosphate (hardest substance in body) does not dissolve in water but corrodes when pH is lower than
5.5 due to acids produced by degradation of food particles by bacteria.
Q10: Assertion (A) : Mg(OH)₂ reacts with with Metal Hydrogen Carbonate.
Reason (R) : Bases dissolved in water are called alkalis.
Answers:
1: (c) A is true but R is false.
2: (a) Both A and R are true and R is the correct explanation of A.
3: (a) Both A and R are true and R is the correct explanation of A.
4: (b) Both A and R are true but R is not the correct explanation of A.
5: (d) A is false but R is true. (should Not be kept)
6: (c) A is true but R is false.
7: (c) A is true but R is false.
8: (b) Both A and R are true but R is not the correct explanation of A.
9: (a) Both A and R are true and R is the correct explanation of A.
10: (d) A is false but R is true.
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