AIIMS Physics: Questions 222 - 224 of 500

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Question number: 222

» Communication System » Propagation of Electromagnetic Waves in the Atmosphere

Appeared in Year: 2006

Assertion-Reason▾

Assertion (Ꭺ)

Electromagnetic waves with frequencies smaller than the critical frequency of ionosphere cannot be used for communication using sky wave propagation.

Reason (Ꭱ)

The refractive index of the ionosphere becomes very high for frequencies higher than the critical frequency.

Choices

Choice (4) Response
a. Both Ꭺ and Ꭱ are false
b. Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ
c. Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ
d. Ꭺ is true but Ꭱ is false

Question number: 223

» Atoms and Nuclei » Radioactive Decay Law

Appeared in Year: 2004

Assertion-Reason▾

Assertion (Ꭺ)

90Sr from the radioactive fail out from a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells.

Reason (Ꭱ)

The energetic β – particles emitted in the decay of 90Sr damage the bone marrow.

Choices

Choice (4) Response
a. Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ
b. Both Ꭺ and Ꭱ are false
c. Ꭺ is true but Ꭱ is false
d. Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

Question number: 224

» Properties of Solids & Liquids » Boyle's Law & Applications

Appeared in Year: 1995

Assertion-Reason▾

Assertion (Ꭺ)

A needle placed carefully on the surface of water may float where a ball of the same material will always sink.

Reason (Ꭱ)

The buoyancy of an object depends both on the material and shape of the object.

Choices

Choice (4) Response
a. Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ
b. Ꭺ is false but Ꭱ is true
c. Ꭺ is true but Ꭱ is false
d. Both Ꭺ and Ꭱ are false

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