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Question 1

Q41. White Phosphorous is represented by which among the following symbols?

P1

P2

P3

P4

Answer

Answer : P4

The most important form of elemental phosphorus from the perspective of applications and chemical literature is white phosphorus. It consists of tetrahedral P4 molecules, in which each atom is bound to the other three atoms by a single bond. This P4 tetrahedron is also present in liquid and gaseous phosphorus up to the temperature of 800 °C when it starts decomposing to P2 molecules
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Question 2

Q42. Which among following is also known as white gold?

Nickel

Rhodium

Platinum

Palladium

Answer

Answer : Platinum

Platinum is a naturally white metal. It doses not need to be alloyed for color. Due to its appearance as white, it is commonly known as White Gold.
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Question 3

Q43. What is the reason that despite being third most abundant element on the Earth’s surface and most abundant chemical substance in the universe, Hydrogen is not found as a gas in Earth’s atmosphere?

It is very reactive and unstable gas

It is so light that readily escapes earth’s gravity

It is not found in free state in nature

None of the above reasons

Answer

Answer : It is so light that readily escapes earth’s gravity

Under ordinary conditions on Earth, elemental hydrogen exists as the diatomic gas, H₂. However, hydrogen gas is very rare in the Earth’s atmosphere (1 ppm by volume) because of its light weight, which enables it to escape from Earth’s gravity more easily than heavier gases. However, hydrogen is the third most abundant element on the Earth’s surface, mostly in the form of chemical compounds such as hydrocarbons and water. Hydrogen gas is produced by some bacteria and algae and is a natural component of flatus, as is methane, itself a hydrogen source of increasing importance.
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Question 4

Q44. With reference to the nuclear fuels, how the Fissile material is different from the Fertile material?
1. While Fissile material undergoes nuclear fission, Fertile material undergoes nuclear fusion
2. While Fissile material can be directly used, Fertile material can not be used directly in nuclear reactors
Choose the correct option from the codes given below:

Only 1 is correct

Only 2 is correct

Both 1 & 2 are correct

Neither 1 nor 2 is correct

Answer

Answer : Only 2 is correct

he fissile material is the one which undergoes nuclear fission (splitting of atom) upon bombardment by slow/fast neutrons. The fissile materials used are Uranium 235, Plutonium239 and Uranium233. (India is the only country in the world to use U 233 fuel, used in Purnima & Kamini Reactors. Fertile material is the one which by itself is not fissionable but will capture the neutron and will get converted to a fissile material. Examples are Uranium 238 becoming Plutonium 239. Thorium 232 becoming Uranium 233 etc.
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Question 5

Q45. Nerve agents are a class of:

phosphorus-containing organic chemicals

sulphur-containing organic chemicals

osmium-containing organic compounds

radon-containing organic compounds

Answer

Answer : phosphorus-containing organic chemicals

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