Science & Biotechnology

41. The waste management technique that involves the use of micro-organisms to remove or neutralize pollutants from a contaminated site is called— [S.S.C. Online Graduate Level (T-I) 3.09.2016 (Shift-I)]

(a) Bio sensor
(b) Bio magnification
(c) Bio remediation
(d) Bio concentration

Correct Answer: (c) Bio remediation

Solution:A system of waste management, Bio-remediation is a technique in which organic components such as bacteria, fungi, or green plants are used to neutralize or decompose pollutants from soil or water. These micro-organisms convert the contaminants into less harmful substances; they absorb pollutants such as salts, and metallic impurities in their tissues.

42. What are the dissolved and suspended impurities in sewage called? [S.S.C. Online Graduate Level (T-I) 11.08.2017 (Shift-III)]

(a) Adulterant
(b) Waste
(c) Solids
(d) Contaminants

Correct Answer: (d) Contaminants

Solution:Impurities suspended in sewage are called contaminants. These are organic chemical substances released into the urban environment, which collect in sewage or sewage through industrial and domestic sources.

43. Which among the following is used in making liquors, medicines, and as a fuel in aircrafts? [S.S.C. Online CHSL (T-I) 16.01.2017 (Shift-I)]

(a) Propyl alcohol
(b) Dimethyl alcohol
(c) Ethyl alcohol
(d) Methyl alcohol

Correct Answer: (c) Ethyl alcohol

Solution:Ethyl alcohol is an organic compound that exists in liquid form at normal temperature and pressure. It is a flammable and volatile compound. The chemical formula of ethyl alcohol is C₂H₅OH.

44. Iron and Manganese present as pollutants in water cannot be removed by— [S.S.C. Online Graduate Level (T-I) 7.09.2016 (Shift-I)]

(a) oxidation followed by settling and filtration
(b) chlorination
(c) ion exchange process
(d) lime soda process or manganese zeolite process

Correct Answer: (b) chlorination

Solution:By chlorination, micro-organisms such as bacteria present in water can be destroyed, but chlorine reacts with metal impurities like iron and manganese to form soluble salts in water, which cannot be separated by filtration.

45. A genetically engineered form of brinjal known as the BT-brinjal has been developed. The objective of this is— [S.S.C. Online Graduate Level (T-I) 6.09.2016 (Shift-II)]

(a) to make it pest resistant
(b) to improve its taste and nutritive value
(c) to make it drought resistant
(d) to make its shelf-life longer

Correct Answer: (a) to make it pest resistant

Solution:Bt Brinjal is a new species of brinjal developed by genetic engineering. In this, a special gene (Cry1AC) of a bacterium named Bacillus thuringiensis was inserted into the brinjal. Due to this, a type of toxin (BT Toxin) is produced, which generates immunity against insects in brinjal. Thus, the purpose of the development of Bt brinjal is to make it insect resistant.

46. Which one of the following is not a greenhouse gas? [S.S.C. Online CHSL (T-I) 19.01.2017 (Shift-II)]

(a) Carbon dioxide
(b) Water vapor
(c) Carbon monoxide
(d) Nitrous oxide

Correct Answer: (c) Carbon monoxide

Solution:Greenhouse gases are responsible for changes in the planet’s atmosphere or climate and ultimately for global warming. Most of these gases are water vapor, carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, ozone, etc.

47. Which of the following is a greenhouse gas or a gas which can deplete the Ozone layer? [S.S.C. Online CHSL (T-I) 23.01.2017 (Shift-III)]

(a) B₂H₆
(b) NF₃
(c) CCl₂F₂
(d) C₆H₆

Correct Answer: (c) CCl₂F₂

Solution:Trichlorofluoromethane (CCl₃F), known as freon-11, or R-11, is a colored gas. Since 1996, R-11 gases have been kept in the category of gases that damage the ozone layer.

48. Which of the following is a greenhouse gas or a gas that can damage the ozone layer? [S.S.C. Online CHSL (T-I) 31.01.2017 (Shift-III)]

(a) Br₂
(b) OF₂
(c) CHCl₂F
(d) CO₂

Correct Answer: (c) CHCl₂F

Solution:Dichlorofluoromethane or Freon 21, R-21, is a hydrochlorofluorocarbon, which is responsible for damaging the ozone layer. Its production and use have been banned in the year 2015 under the Montreal Treaty.

49. Which of the following is a greenhouse gas or a gas which can deplete the ozone layer? [S.S.C. Online CHSL (T-I) 1.02.2017 (Shift-I)]

(a) N₂O
(b) AsH₃
(c) N₂
(d) C₅H₁₂

Correct Answer: (a) N₂O

Solution:Nitrous oxide gas is responsible for the depletion of the ozone layer.

50. Which of the following is a greenhouse gas or a gas which can deplete the ozone layer? [S.S.C. Online CHSL (T-I) 7.02.2017 (Shift-I)]

(a) BBr₃
(b) NH₃
(c) CH₂N₂
(d) CCl₂F₂

Correct Answer: (c) CH₂N₂

Solution:Dichlorofluoromethane (R-12) class gas CCl₂F₂ is responsible for ozone depletion.