Question 11: Common salt besides being used in kitchen can also be used as the raw material for making
Explanation: Soda is prepared by electrolytic decomposition of brine (NaCl solution). Baking soda is prepared by reaction between brine and ammonia. Slaked lime is made from limestone. Bleaching powder is made from chlorine (which is a byproduct of electrolytic decomposition of brine.
Question 12: One of the constituents of baking powder is sodium hydrogencarbonate, the other constituent is
Question 13: To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is
Explanation: Tooth decay happens because of action of acid on tooth enamel. The acid comes due to action of bacteria on food particles in mouth. A base helps in neutralizing the effect of acid, and thus helps in preventing tooth decay.
Question 14: Which of the following statements is correct about an aqueous solution of an acid and of a base?
Explanation: We know that pH of acid is less than 7, while that of base is more than 7. Increase in pH means increase in basic property.
Question 15: The pH of the gastric juices released during digestion is
Explanation: pH of any acid is always less than 7
Question 16: Which of the following phenomena occur, when a small amount of acid is added to water?
Explanation: Whenever an acid is dissolved in water, the acid dissociates into ions. Moreover, dissolution in water results in dilution of acid. Neutralisation and salt formation are more or less similar because neutralization is the process and salt formation is the result of this process. But neutralization happens when an acid reacts with a base.
Question 17: Which one of the following can be used as an acid–base indicator by a visually impaired student?
Explanation: Vanilla essence will show change in smell in presence of acid/base. A visually impaired student cannot perceive change in colour but can easily detect change in smell.
Question 18: Which of the following substance will not give carbon dioxide on treatment with dilute acid?
Explanation: Lime is calcium hydroxide, which means carbon is not present in this compound. Marble and limestone are calcium carbonate, while baking soda is sodium bicarbonate. In other words, carbon is present in these three compounds. And we cannot make carbon dioxide without carbon.
Question 19: Which of the following is acidic in nature?
Question 20: In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus (Given Figure) was set up. Which among the following statement(s) is(are) correct?
Explanation: Acid, base and even salt can be used for making electrolyte solution.
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