For the Assertion (A) and Reason (R) below, choose the correct alternative.
Assertion(A) : An iron ball floats on mercury but gets immersed in water.
Reason (R) : The specific gravity of iron is more than that of mercury.
Answer: C
Iron with specific gravity less than that of mercury but more than that of water, floats in the former but gets immersed in the second
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Assertion (A) : Cotton is grown in alluvial soils.
Reason (R) : Alluvial soils are very fertile.
Answer: A
Alluvial soils comprising of silt and sand carried down by the rivers, are very fertile. However, cotton is grown in black soil that suits its mineral requirements
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Assertion (A) : There is no vaccine for AIDS.
Resson (R) : The AIDS virus changes its genetic code
Answer: A
A vaccine contains the inactivated germs of the disease. But the AIDS virus changes its genetic code and so on vaccine has been invented for it.
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Assertion (A) : We feel colder on mountains than on plains.
Reason (R) : Temperature decreases with altitude.
Answer: A
Higher above the sea level, temperature decreases at the rate of 1 degree centigarade for every 165 me-tres of ascent making mountain peaks colder.
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Assertion (A) : Weeds should not be allowed to grow along with the crops.
Reason (R) : Weeds leave no space for plants to grow.
Answer: C
Weeds should not be allowed to grow along with the crops because they consume the plant nutrients.
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Assertion (A) : Razia Sultan was the daughter of Iltutmish.
Reason (R) : Iltutmish was a rebel.
Answer: C
litutmish was a ruler of slave dynasty and Razia was his daughter.
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Assertion (A) : In India, females have higher life expectancy than the males.
Reason (R) : Females receive a better diet.
Answer: D
In India, due to high birth rate and due to neglect, females have a lower life expectancy than the males and although females need a better diet, they do not receive it.
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Assertion(A) : The steam engine was invented by James Watt.
Reason (R) : There was a problem of taking out water from flooded mines
Answer: A
The problem of pumping out water from the flooded mines provided the need of a self working engine, which led James Watt to invent the same.
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Assertion (A) : An atom is neutral despite the charged particles in it.
Reason (R) : The neutrons do not have any charge.
Answer: B
An atom contains the positively charged protons and an equal number of negatively charged electrons So, it is neutral
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Assertion (A) : Leakages in household gas cylinders can be detected.
Reason (R) : LPG has a strong smell.
Answer: C
Leakages in household gas cylinders can be detected because of the strong smell of ethyl merceptan mixed with LPG.
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