31. Match the acids given in Column (A) with their correct source given in Column (B)
| Column (A) | Column (B) |
|---|---|
| (a) Lactic acid | (i) Tomato |
| (b) Acetic acid | (ii) Lemon |
| (c) Citric acid | (iii) Vinegar |
| (d) Oxalic acid | (iv) Curd |
(a) — (iv)
(b) — (iii)
(c) — (ii)
(d) — (i)
32. Match the important chemicals given in Column (A) with the chemical formulae given in Column (B)
| Column (A) | Column (B) |
|---|---|
| (a) Plaster of Paris | (i) Ca(OH)₂ |
| (b) Gypsum | (ii) CaSO₄·1/2 H₂O |
| (c) Bleaching Powder | (iii) CaSO₄·2H₂O |
| (d) Slaked Lime | (iv) CaOCl₂ |
33. What will be the action of the following substances on litmus paper?
Dry HCl gas, Moist ened NH₃ gas, Lemon juice, Carbonated soft drink, Curd, Soap solution.
| Substance | Action on Litmus paper |
|---|---|
| Dry HCl gas | No change |
| Moistened NH₃ gas | Turns red to blue |
| Lemon juice | Turns blue to red |
| Carbonated soft drink | Turns blue to red |
| Curd | Turns blue to red |
| Soap solution | Turns red to blue |
34. Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.
35. What happens when nitric acid is added to egg shell?
36. A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?
37. How would you distinguish between baking powder and washing soda by heating?
38. Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through lime water, turns it milky. Identify A, B and C.
39. In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
40. Fill in the missing data in the following table
| Name of the salt | Formula | Salt obtained from — Base | Salt obtained from — Acid |
|---|---|---|---|
| (i) Ammonium chloride | NH₄Cl | NH₄OH | — |
| (ii) Copper sulphate | — | — | H₂SO₄ |
| (iii) Sodium chloride | NaCl | NaOH | — |
| (iv) Magnesium nitrate | Mg(NO₃)₂ | — | HNO₃ |
| (v) Potassium sulphate | K₂SO₄ | — | — |
| (vi) Calcium nitrate | Ca(NO₃)₂ | Ca(OH)₂ | HNO₃ |
41. What are strong and weak acids? In the following list of acids, separate strong acids from weak acids.
Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.
42. When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.