Case-based study question set (as per CBSE Class 10 pattern) based on the chapters “Chemical Reactions and Equations” and “Acids, Bases and Salts

Case-based study question set (as per CBSE Class 10 pattern) based on the chapters “Chemical Reactions and Equations” and “Acids, Bases and Salts” with passage, questions, and answers.

---

🧪 Case Study Question – 1

Chapter: Chemical Reactions and Equations

Case:
Ravi performed an experiment in the chemistry lab. He took a clean magnesium ribbon and burned it in the presence of oxygen. A white powder was formed which was collected and mixed with water. The resulting solution turned red litmus paper blue. He also noticed that the magnesium ribbon produced a bright white flame when burnt.

Based on the above, answer the following questions:

Q1. Write the balanced chemical equation for the reaction between magnesium and oxygen.
Q2. What type of chemical reaction is this?
Q3. Why did the red litmus turn blue?
Q4. What is the nature of the oxide formed in this reaction?
Q5. Is this an exothermic or endothermic reaction?

---

✅ Answers:

A1.    2MgO  +  O2------------------------> 2MgO

A2. Combination reaction

A3. Because magnesium oxide is basic in nature.

A4. Magnesium oxide is a basic oxide.

A5. It is an exothermic reaction.

---

🧪 Case Study Question – 2

Chapter: Acids, Bases and Salts

Case:
Ankita added dilute hydrochloric acid to a beaker containing zinc granules. She observed brisk effervescence and collected the gas evolved. When a burning matchstick was brought near the mouth of the test tube, the gas produced a pop sound. Later, she tested the pH of the resulting solution and found it to be nearly neutral.

Answer the following:

Q1. Write the chemical equation for the reaction between zinc and HCl.
Q2. Name the gas evolved and the test used to identify it.
Q3. Why was there effervescence during the reaction?
Q4. What does the pop sound indicate?
Q5. Why was the final solution nearly neutral?

---

✅ Answers:

A1.    Zn + HCl ---------------------> ZnCl2 + H2

A2. Hydrogen gas; confirmed by the pop sound test.

A3. Due to the evolution of hydrogen gas.

A4. Presence of hydrogen gas.

A5. Because zinc chloride is a neutral salt and excess acid was not present.