- Choose the correct option.
- Temperature is measured in:
- Calorie ii. erg. iii. joule. iv degree Celsius.
Answer: iv. Degree Celsius
- Which of the following is true for sea breeze?
- Cool air flows from the sea towards the land.
- Hot air flows from the sea towards the land.
- Hot air flows from land towards the sea.
- Cool air flows from the land towards the sea.
Answer: i. Cool air flows from the sea towards the land.
- Which type of thermometer is used to measure the temperature of chemicals with high accuracy ?
- Clinical thermometer. ii. Laboratory thermometer. iii. Digital thermometer. iv Six’s thermometer.
Answer. ii. Laboratory thermometer
- The surface of an object is given a darker colour because it is a:
- Bad conductor of heat. ii. Good reflector of heat. iii. Bad emitter of heat. iv. Good absorber of heat.
Answer: iv. Good absorber of heat
- Match the columns.
| Column A | Column B |
| a. Zinc carbonate | i. Mineral acid |
| b. Magnesium oxide | ii. Fertiliser. |
| c. Sulphuric acid | iii. Organic acid |
| d. ammonium sulphate | iv. Calamine |
| Ascorbic acid | v.Antacid |
| Column A | Column B |
| a. Zinc carbonate | iv. Calamine |
| b. Magnesium oxide | v. Antacid |
| c. Sulphuric acid | i. Mineral acid |
| d. ammonium sulphate | ii. Fertiliser |
| Ascorbic acid | iii. Organic acid. |
Q3.Assertion- Reasoning questions.
For question number (i) and (ii) ,two statements are given -one labelled as assertion(A) and the other labelled as Reason ( R ). Select the correct answer to these questions From the codes (a), (b),(c) and (d) is given below.
- Both assertion(A) and Reason (R) are true and Reason (R) is the correct explanation of the assertation (A)
- Both assertion (A) and reason are true and Reason (R) is not the correct explanation of the assertation (A)
- Assertion (A) is true but reason (R) is false
- Assertion (A) is false, but reason (R) is true.
- Assertion (A): The reaction between an acid and base is known as a neutralisation reaction.
Reason (R ) Salt and water are formed as products in a neutralization reaction.
- Assertion (A) Hydrochloric acid is a stronger acid than acetic acid.
Reason (R) Acetic acid dissociates completely whereas hydrochloric acid dissociates partially
Assertion-Reasoning Questions
For question numbers (i) and (ii), two statements are given – one labeled as Assertion (A) and the other labeled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c), and (d) given below:
(a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.
(i) Assertion (A): The reaction between an acid and a base is known as a neutralisation reaction.
Reason (R): Salt and water are formed as products in a neutralisation reaction.
Correct Answer: (a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
(ii) Assertion (A): Hydrochloric acid is a stronger acid than acetic acid.
Reason (R): Acetic acid dissociates completely, whereas hydrochloric acid dissociates partially.
Correct Answer: (c) Assertion (A) is true, but Reason (R) is false.
Question 4.Answer the following in one sentence:
a. What are weak acids?
Answer. Weak acids are acids that do not fully dissociate into their ions in solution.
b. What will be the colour of a basic solution after adding a phenolphthalein indicator?
Answer. The color of a basic solution after adding phenolphthalein indicator will be pink.
c. What salt is used in the manufacture of gunpowder?
Answer.Potassium nitrate is the salt used in the manufacture of gunpowder.
Question 5. Answer the following questions in 2-3 sentences.
a. What are indicators?
Answer. Indicators are substances that change color when added to an acidic or basic solution, allowing us to determine the pH of the solution. Common examples include litmus paper, phenolphthalein, and methyl orange.
b. What is an alkali? Give one example.
Answer. An alkali is a base that dissolves in water to produce hydroxide ions (OH⁻). An example of an alkali is sodium hydroxide (NaOH).
c. Why is an antacid tablet taken when a person suffers from acidity?
Answer. An antacid tablet is taken to neutralize excess stomach acid, providing relief from the discomfort and pain caused by acidity. The antacid contains basic substances that react with and neutralize the stomach acid.
Question 6. Answer the following questions in 3-4 sentences.
a. Why is factory waste neutralised before disposing it into water bodies?
Answer.Factory waste is neutralised before disposal to prevent harmful effects on the environment and aquatic life. Acidic or basic waste can alter the pH of water bodies, harming plants, animals, and microorganisms. Neutralisation ensures that the waste is safe and minimizes its impact on the ecosystem.
b. Explain why a test tube turns hot after a neutralisation reaction.
Answer. A test tube turns hot after a neutralisation reaction because the reaction between an acid and a base is exothermic. This means that it releases heat energy, which is why the test tube feels warm to the touch.
c. Explain what acid rain is.
Answer.Acid rain is precipitation that contains high levels of sulfuric and nitric acids, formed from the emissions of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) from industrial processes and vehicles. These pollutants react with water vapor in the atmosphere to produce acids, which then fall to the ground as rain, harming ecosystems, buildings, and human health.