Class 10 Science Chapter 2
Acid, Bases and Salts
Important Questions

Here are some critical Chapter 2 Acid, Bases and Salts problems for Class 10 Science. These inquiries are intended to aid students in studying for and performing well on the CBSE Class 10 Science Examination 2023–24. Students can clear up their concerns and be ready for the exams by practising different types of questions. By answering these questions, you'll increase your confidence while also sharpening your problem-solving abilities.

Introduction

 In Chapter 2 of Acid, Bases and Salts you will learn about The Chemical Properties of Acids and Bases, Common Characteristics of Acids and Bases, Strong Acid and Base Solution and Characteristics of Salts.

 Class 10 Acid Bases and Salts Important Questions and Answers

Q 1. During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to:

Options

(a) Absorb the evolved gas
(b) Moisten the gas
(c) Absorb moisture from the gas
(d) Absorb Cl– ions from the evolved gas

Ans. (c)

Explanation:
The role of calcium chloride taken in the guard tube is to absorb moisture from the gas. This is because calcium chloride is used as a drying agent which absorbs moisture from the hydrogen chloride (HCI) gas.

Q 2. In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus was set up. Which among the following statement(s) is(are) correct?

(i) Bulbs will not glow because electrolyte is not acidic.
(ii) Bulb will glow because NaOH is a strong base and furnishes ions for conduction.
(iii) Bulb will not glow because the circuit is incomplete.
(iv) Bulb will not glow because it depends upon the type of electrolytic solution.

Options

(a) (i) and (iii)
(b) (ii) and (iv)
(c) (ii) only
(d) (iv) only

Ans. (c)

Explanation:
Electrical Conductivity is an ability of an electrolyte to carry a current. It is a medium which contains ions and because of the moment of those charged ions when placed in an electric field, there would be conduction of electricity. NaOH is a strong base which would be responsible for the electrical conductivity.

Q 3. Give balanced chemical equation for reaction of acids with metal carbonate.

Explanation:
Reaction of acids with metal carbonate: Acids when react with metal carbonates give carbon dioxide gas and respective salts along with water.
Metal carbnate + Acid → Salt + Carbon dioxide + Water
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

Q 4. Write an equation for the reaction of iron with steam. Name the compound of iron obtained.

Explanation:
Metal reacts with steam to form metal oxide and hydrogen gas. Here, iron reacts with steam to form iron oxide and hydrogen gas. The reaction of iron with steam can be given as:
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)

Q 5. Answer the given question:
Crystals of a substance changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved.

Explanation:
Crystals of a substance which changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down are copper sulphate or more specifically hydrated copper sulphate.
Its chemical formula is CuSO₄.5H₂O
The phenomena involved is due to the presence of molecules of water of crystallisation in the molecule. Water of crystallisation is the fixed number of water molecules that are present in one formula unit of a salt. When we heat the crystals of hydrated copper sulphate this water is removed and the salt turns white. But when it is allowed to cool down in open air then it regains its lost water of crystallisation and hence regains its colour also.

CBSE Class 10 Science Chapter wise Important Questions

Conclusion

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Frequently Asked Questions

Q1: What is salt in acids, bases and salts?

Ans: In chemistry, a salt is a substance obtained by the reaction of an acid and a base.Salts are composed of positive ions (cations) of bases and negative ions (anions) of acids. The reaction of acid and base is called the neutralisation reaction.

Q2: Is NH₄Cl a basic salt?

Ans: Ammonium chloride (chemical formula \(NH_4Cl)\ is an acid salt because it is a salt of a strong acid (i.e. hydrochloric acid) and a weak base (i.e. ammonium hydroxide).

Q3:  What are the 2 types of acids?

Ans: There are two basic types of acids: organic and inorganic acids. Inorganic acids are sometimes referred to as mineral acids. As a group, organic acids are generally not as strong as inorganic acids. The main difference between the two is the presence of carbon in the compound; inorganic acids do not contain carbon.
Inorganic acids – Inorganic acids are often termed mineral acids. The anhydrous form may be gaseous or solid. An inorganic anhydride is an oxide of metalloid which can combine with water to form an inorganic acid.
Example:Sulphuric acid (H₂SO₄) ,Phosphoric acid (H₃PO₄) ,Nitric acid (HNO₃)
‍Organic acids – Organic acids are corrosive and toxic. Corrosivity is a form of toxicity to the tissues that the acid contacts. Organic acids and their derivatives cover a wide range of substances. They are used in nearly every type of chemical manufacture. Because of the variety in the chemical structure of the members of the organic acid group.
Example:Acetic acid ,Citric acid ,Formic acid

Q4:  Is salt basic or acidic?

Ans: The salt is basic only when it contains a weak acid conjugate base. For example, sodium chloride contains chloride (Cl^-), the conjugate base of HCl.

Q5: What happens when salt reacts with HCl?

Ans: When an acid reacts with metal, a salt and hydrogen are produced:
acid + metal → salt + hydrogen
The salt that is produced depends upon which acid and which metal reacts.Sodium metal reacts with hydrochloric acid which produces hydrogen gas and sodium chloride.
2Na(s)+2HCl(aq)→2NaCl(aq)+H₂(g)