Revision Series | Science | General Science | 64

December 29, 2023

Which one of the given is incorrect?

(A) Acids turns blue litmus paper red
(B) Aqueous solutions of acids conduct electricity
(C) Acids react with certain metals to form hydrogen gas
(D) None of these

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Answer- D

Acids turns blue litmus paper red. acids turn blue litmus to red. Litmus turns blue when it comes into contact with acids. When blue litmus paper is placed in an acidic solution, it becomes red. However, when placed in a basic or neutral substance, it will remain blue.
Aqueous solutions of acids conduct electricity. Acid dissociates into ions in aqueous solution. The migration of movements helps in conducting electricity. Thus, aqueous solution of acid conduct electricity.
Acids react with certain metals to form hydrogen gas.

Regarding the myopia, consider the following statements:
1. In a myopic eye, the image of a distant object gets formed behind the retina.
2. Myopia is caused by shortening of eyeball.
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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Answer- D

Myopia is also known as near sightedness. A person with myopia can see nearby objects clearly but cannot see distant objects distinctly. Myopia is caused by two reasons:

Excessive curvature of eye lens.
Elongation of eyeball.

A person with this defect has the far point nearer than infinity. Such a person may see clearly upto a distance of a few metres. In a myopic eye, the image of a distant object is formed in front of the retina and not at the retina itself.

Due to their semiconductor properties, which non-metals are used in computers and T.V.?

(A) Carbon
(B) Bromine
(C) Silicon
(D) Fluorine

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Answer- C

Which one of the following statements is not true?

(A) The molecules in a solid vibrate about a fixed position
(B) The molecules in a liquid are arranged in a regular pattern
(C) The molecules in a gas exert negligibly small forces on each other, except during collisions
(D) The molecules of a gas occupy all the space available

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Answer- B

James Chadwick is associated with discovery of which of the following?

(A) Atom
(B) Neutron
(C) Proton
(D) Electron

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Answer- B

Which of the following phenomena always results in the cooling effect?

(A) Condensation
(B) Evaporation
(C) Sublimation
(D) None of these

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Answer- B

The cooling effect is produced in the room when a grass-screen (khaskhas) soaked with water is placed in front of door. It is due to fact that warm and dry air helps in evaporation of water present in the grass-screen. And due to evaporation, the cooling effect is produced. As we know that evaporation is the cooling phenomena, or produces a cooling effect.

Which of the following is not a measurement of temperature?

(A) Celsius
(B) Fahrenheit
(C) Kelvin
(D) Pascal

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Answer- D

Pascal is the SI unit of Pressure whereas Celsius, Fahrenheit and Kelvin are the scales used in thermometer(a device used to measure temperature). The SI unit of temperature is Kelvin.

Tiny pores are found on the surface of the leaves of plants. These pores are called stomata. These stomata surrounded by the kidney shaped guard cells provide many vital functions to the plants.
Which of the following functions is not served by the stomata for the plants?

(A) Exchange of gases, particularly CO2 and O2, with atmosphere
(B) Loss of water in the form of vapours during transpiration
(C) Helps to create pressure for the water to rise upward, by its process of transpiration
(D) Helps the leaves to carry out the process of photosynthesis

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Answer- D

Arrange the following components in decreasing order according to their percentage present in air.

(A) Nitrogen, Oxygen, Argon, Carbon dioxide.
(B) Oxygen, Argon, Carbon dioxide, Nitrogen.
(C) Nitrogen, Carbon dioxide, Oxygen, Argon.
(D) Nitrogen, Oxygen, Carbon dioxide, Argon.

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Answer- A

the major components of the air are: Nitrogen – 78% Oxygen – 20% Argon – 0.93% Carbon dioxide – 0.031%. Other gases such as Neon, Helium, Hydrogen etc, are present in trace amounts. The increasing order of the boiming points of the above gases is: Nitrogen (lowest) Argon Oxygen Carbon dioxide