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A farmer was unhappy because of his low crop yield. He discussed the problem with an agricultural scientist and realised that the soil of his field was either too acidic or too basic. What remedy would you suggest the farmer to neutralise the soil?

Soln: If the soil is too acidic, it is treated with bases such as quick lime (calcium oxide) or slaked lime (calcium hydroxide). If the soil is too basic, organic matter is added to it. Organic matter releases acids which neutralise the basic nature of the soil.

Questions & Answers

A farmer was unhappy because of his low crop yield. He discussed the problem with an agricultural scientist and realised that the soil of his field was either too acidic or too basic. What remedy would you suggest the farmer to neutralise the soil?

18. Match the substances in Column I with those in Column II. Column I Column II a) Tartaric acid i) Soap b) Calcium hydroxide ii) Curd c) Formic acid iii) Unripe mangoes d) Sodium Hydroxide iv) Ant&rsquo;s sting e) Lactic acid v) Lime water

Form a sentence using the following words – baking soda, ant bite, moist, effect, neutralised, rubbing.

While playing in a park, a child was stung by a wasp. Some elders suggested applying the paste of baking soda and other lemon juice as the remedy. Which remedy do you think is appropriate and why?

Paheli is suffering from indigestion due to acidity. Is it advisable to give her orange juice in this situation, and why?

Look at the given reaction. Hydrochloric acid + Sodium hydroxide (base) → Sodium chloride (salt) + Water Sodium chloride formed in this reaction remains in solution form. Can we get solid sodium chloride from this solution? Suggest a method (if any).

Which of the following is an acid-base indicator? (a) Vinegar (b) Lime water (c) Turmeric (d) Baking soda

On adding the phenolphthalein indicator to a colourless solution, no change is observed. What is the nature of this solution? (a) Basic (b) Either acidic or basic (c) Either acidic or neutral (d) Either basic or neutral

Which of the following set of substances contain acids? (a) Grapes, lime water (b) Vinegar, soap (c) Curd, milk of magnesia (d) Curd, vinegar

A solution changes the colour of the turmeric indicator from yellow to red. The solution is (a) basic (b) acidic (c) neutral (d) either neutral or acidic

A neutralisation reaction is a (a) physical and reversible change. (b) a physical change that cannot be reversed. (c) chemical and reversible change. (d) the chemical change that cannot be reversed.

‘Litmus’, a natural dye, is an extract of which of the following? (a) China rose (Gudhal) (b) Beetroot (c) Lichen (d) Blueberries (Jamun)

When the soil is too basic, plants do not grow well in it. To improve its quality what must be added to the soil? (a) Organic matter (b) Quick lime (c) Slaked lime (d) Calamine solution

Phenolphthalein is a synthetic indicator, and its colours in acidic and basic solutions, respectively, are (a) red and blue. (b) blue and red. (c) pink and colourless. (d) colourless and pink

Turmeric is a natural indicator. On adding its paste to acid and base separately, which colours would be observed (a) Yellow in both acid and base. (b) Yellow in acid and red in the base. (c) Pink in acid and yellow in the base. (d) Red in acid and blue in the base.

Products of a neutralisation reaction are always (a) an acid and a base. (b) an acid and a salt. (c) salt and water. (d) a salt and a base.

The correct way of making a solution of acid in water is to (a) add water to acid. (b) add acid to water. (c) mix acid and water simultaneously. (d) add water to acid in a shallow container.

18. Match the substances in Column I with those in Column II. Column I Column II a) Tartaric acid i) Soap b) Calcium hydroxide ii) Curd c) Formic acid iii) Unripe mangoes d) Sodium Hydroxide iv) Ant’s sting e) Lactic acid v) Lime water