SOLVED PAPER 2020 (CDS) (II) (General Studies)

Total Questions: 120

91. Under the kingdom– Plantae, which of the following individuals are predominantly aquatic?

Correct Answer: (b) Algae
Solution:Under the kingdom– plantae, Phyllum-Algae have individuals that are predominantly aquatic (both fresh water and marine).

These are chlorophyll bearing simple, thalloid, autotrophic organism. They occurs in a variety of habitats like standing water, moist stones, soils and woods.

92. All the individuals of a particular organism, such as rose plants, belong to a taxonomic category called

Correct Answer: (a) Species
Solution:All the individuals of a particular organism, such as rose plants belongs to a taxonomic category called species because species is a group of individual organisms with fundamental similarities.

93. Pearls are harvested from

Correct Answer: (d) oyster
Solution:Pearls are harvested from oyster. A pearl is an ulcer formed in the oysters when an unknown outside particle get into the shell. It is due to the stress that the oysters produce nacre that will eventually become the pearl in a couple of years. So, basically the pearl is the result of a disease in the oyster’s body.

94. Wings of birds and bats are considered analogous structures because they have

Correct Answer: (b) different origin and common function
Solution:Wings of birds and bats looks alike and perform same function of flying. But anatomically they are different in origin. Birds have feathers projecting back from lightweight, fused arms and hand bones. Bats have flexible, relatively short wings with membranes stretched between elongated fingers. Thus, these are analogous.

95. Apart from hyper acid secretion, peptic ulcers are also developed due to bacterial infection. The causative agent is

Correct Answer: (a) Helicobacter pylor
Solution:Helicobacter pylori is the causative agent of peptic ulcer. It is a sore that develops on the living of the oesophagus, stomach or small intestine. Ulcer occurs when stomach acid damages the living of the digestive tract. Common causes of ulcer include the bacteria H. pylori and anti- inflammatory pain relievers including aspirin.

96. A mixture of sodium chloride (salt) and ammonium chloride can be separated by

Correct Answer: (a) sublimation
Solution:A mixture of sodium chloride (salt) and ammonium chloride can be separated by sublimation. This technique involves the conversion of a solid direct into vapour. On heating, ammonium chloride changes from solid state to ammonia vapours. Here, ammonium chloride can be sublimed whereas sodium chloride cannot be sublimed.

97. Symbol of element was introduced by

Correct Answer: (a) John Dalton
Solution:Symbol of element was introduced by John Dalton. Symbols are the representation of an element. It is simple to use the symbol of an element rather than writing a whole word.

Some symbols along with elements are as follows : 

98. Identify the correct pair of elements among the following which are liquid at room temperature and standard pressure.

Correct Answer: (d) Bromine and Mercury
Solution:Bromine and Mercury is the pair of element which are liquid at room temperature and standard pressure. Bromine is a liquid non-metal whereas mercury is a liquid metal.

99. Which one of the following oxides shows both acidic and basic behaviour?

Correct Answer: (a) Zinc oxide
Solution:

Zinc oxide (ZnO) shows both acidic and basic behaviour. It reacts with both acids and bases to form salt and water.

100. Silver articles turn black when kept in the open for longer time due to the formation of

Correct Answer: (d) Ag₂S
Solution:Silver articles turn black when kept in the open for longer time due to the formation of silver sulphide (Ag₂S). Silver metal reacts with sulphur present in the atmosphere and forms Ag₂S. Complete reaction is as follows

2Ag + S → Ag₂S