Correct Option (c):
Assertion (A) states that the boiling point of water decreases as the altitude increases. This statement is true. The boiling point of a liquid is defined as the temperature at which its vapor pressure equals the surrounding atmospheric pressure. As altitude increases, the atmospheric pressure decreases because there is a smaller column of air above exerting pressure. Consequently, water requires less heat energy (a lower temperature) for its vapor pressure to match the reduced external atmospheric pressure, leading to a lower boiling point.
Reason (R) states that the atmospheric pressure increases with altitude. This statement is false. In reality, atmospheric pressure decreases with increasing altitude. This is due to the reduction in the density and amount of air molecules above a given point at higher elevations.
Since Assertion (A) is true and Reason (R) is false, option (c) is the correct choice.
Incorrect Options:
Options (a) and (b) are incorrect because they both assume Reason (R) is true, which is factually incorrect. Atmospheric pressure decreases, not increases, with altitude.
Option (d) is incorrect because it states that Assertion (A) is false. However, it is a well-established scientific fact that the boiling point of water decreases at higher altitudes due to lower atmospheric pressure.