Answers Assignment No. – 1 Acids, Bases and Salts | Class 10th

Answers

Assignment No. – 1

Acids, Bases and Salts

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Ans 1: An acid is a compound, which releases hydronium ions (H₃O⁺) as the only positive ions in solution.

An alkali is a compound, which releases hydroxyl ions (OH^-) as the only negative ions in solution.

A salt is one of the products of neutralization between an acid and a base; water being the only other product.

OR

A salt gives positive ions other than H⁺ ion and negative ions other than OH^- ion in solution.

Ans 2:        HCl = 1     CH₃COOH = 1         H₂SO₄ = 2       H₃PO₄ = 3.

Ans 3. Neutralization is essentially a chemical reaction between H₃O⁺ ions of an acid with OH^- ions of the base, to give undissociated molecules of water.

Ans 4. A strong acid is one, which is almost completely dissociated in solution.
Examples: Dilute nitric acid, dilute sulphuric acid and dilute hydrochloric acid. A weak acid is one, which is only partially ionized in solution (degree of dissociation is >30%). Examples: Acetic acid, carbonic acid and sulphurous acid.

Ans 5: The common name of the compound CaOCl₂ is bleaching powder.

Ans 6: Calcium hydroxide [Ca(OH)₂], on treatment with chlorine, yields bleaching powder.

Ans 7: Washing soda (Na₂CO₃.10H₂O) is used for softening hard water.

Ans 8: When a solution of sodium hydrogen carbonate is heated, sodium carbonate and water are formed with the evolution of carbon dioxide gas.

NaHCO₃ → Na₂CO₃ + H₂O + CO₂ ↑

Ans 9: The chemical equation for the reaction of Plaster of Paris and water can be represented as

Ans 10. Acetic acid is called a monobasic acid because only one of the 4 'H' atoms of the acid is released as H⁺ ion in solution.