Which one of the following is present in the largest amount in terms of per cent by mass in the earth’s crust?
- (a)Silicon
- (b)Oxygen
- (c)Carbon
- (d)Calcium
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Official answer(b) Oxygen
Other questions on Chemistry
Artificial way of causing rainfall to reduce air pollution makes use of
- (a)silver iodide and potassium iodide
- (b)silver nitrate and potassium iodide
- (c)silver iodide and potassium nitrate
- (d)silver nitrate and potassium chloride
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Official answer(a) silver iodide and potassium iodide
In which of the following are hydrogels used ? 1. Controlled drug delivery in patients 2. Mobile air-conditioning systems 3. Preparation of industrial lubricants Select the correct answer using the code given below :
- (a)1 only
- (b)1 and 2 only
- (c)2 and 3 only
- (d)1, 2 and 3
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Official answer(a) 1 only
Water can dissolve more substances than any other liquid because
- (a)it is dipolar in nature
- (b)it is a good conductor of heat
- (c)it has high value of specific heat
- (d)it is an oxide of hydrogen
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Official answer(a) it is dipolar in nature
In India, the use of carbofuran, methyl parathion, phorate and triazophos is viewed with apprehension. These chemicals are used as
- (a)pesticides in agriculture
- (b)preservatives in processed foods
- (c)fruit-ripening agents
- (d)moisturising agents in cosmetics
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Official answer(a) pesticides in agriculture
Which of the following is/are the example/examples of chemical change? 1. Crystallization of sodium chloride 2. Melting of ice 3. Souring of milk Select the correct answer using the code given below.
- (a)1 and 2 only
- (b)3 only
- (c)1, 2 and 3
- (d)None
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Official answer(b) 3 only
Chlorination is a process used for water purification. The disinfecting action of chlorine is mainly due to
- (a)The formation of hydrochloric acid when chlorine is added to water
- (b)The formation of hypochlorous acid when chlorine is added to water
- (c)The formation of nascent oxygen when chlorine is added to water
- (d)The formation of hydrogen when chlorine is added to water
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Official answer(b) The formation of hypochlorous acid when chlorine is added to water