Which one of the following is NOT true for bleaching powder?
- A.It is used as a reducing agent in chemical industries
- B.It is used for bleaching wood pulp in paper factories
- C.It is used for disinfecting drinking water
- D.It is used for bleaching linen in textile industry
Correct answer
Explanation
The correct answer is A. Bleaching powder is an oxidising agent, not a reducing agent, so this statement is the false one.
Bleaching powder, calcium oxychloride (CaOCl₂), is made by passing chlorine gas over dry slaked lime, Ca(OH)₂. With water or a dilute acid it releases chlorine, which gives up nascent oxygen; that oxygen oxidises coloured substances into colourless ones and kills germs. This is why it is used in chemical industries as an oxidising agent, and why it bleaches and disinfects. On standing in air it slowly loses chlorine, so it is stored in airtight containers.
B is true because bleaching powder is used to bleach wood pulp in paper mills.
C is true because it is widely used to disinfect drinking water and swimming pools.
D is true because it bleaches cotton and linen in the textile industry.
Exam tip: bleaching powder is CaOCl₂, made from Cl₂ and dry slaked lime; it bleaches by oxidation.
Practice Questions
View allRecently, there was a growing awareness in our country about the importance of Himalayan nettle (Girardinia diversifolia) because it is found to be a sustainable source of
- A.anti-malarial drug
- B.biodiesel
- C.pulp for paper industry
- D.textile fibre
Show answer
The Himalayan nettle yields a strong natural fibre that can be spun and woven into cloth. Girardinia diversifolia, known as Himalayan giant nettle or allo, is a stinging shrub that grows wild in the moist forests of the Himalayas, including Uttarakhand, Himachal Pradesh and the North-east, as well as Nepal.
Read the full explanation →Which of the following statements are correct regarding the general difference between plant and animal cells ? 1. Plant cells have cellulose cell walls whilst animal cells do not. 2. Plant cells do not have plasma membrane unlike animal cells which do. 3. Mature plant cell has one large vacuole whilst animal cell has many small vacuoles. Select the correct answer using the code given below:
- A.1 and 2 only
- B.2 and 3 only
- C.1 and 3 only
- D.1,2 and 3
Show answer
Plant cells have a cellulose wall and one large central vacuole, but they do have a plasma membrane, just like animal cells.
Read the full explanation →Consider the following statements : 1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue. 2. Sexual transmission of Zika virus disease is possible. Which of the statements given above is/are correct ?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
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Zika is spread mainly by the Aedes mosquito that also carries dengue, and it can pass between sexual partners. The Zika virus is a flavivirus first identified in Uganda's Zika forest in 1947.
Read the full explanation →What is the importance of using Pneumococcal Conjugate Vaccines in India ? 1. These vaccines are effective against pneumonia as well as meningitis and sepsis. 2. Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced. 3. These vaccines have no side effects and cause no allergic reactions. Select the correct answer using the code given below :
- A.1 only
- B.1 and 2 only
- C.3 only
- D.1, 2 and 3
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Read the full explanation →A ball is thrown vertically upward with a speed of 40 m/s. The time taken by the ball to reach the maximum height would be approximately
- A.2 s
- B.3 s
- C.4 s
- D.5 s
Show answer
The ball keeps slowing down by about 9.8 m/s every second until its speed becomes zero at the top, which takes 40 ÷ 9.8 ≈ 4 seconds.
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