Correct Answer : Option C) 1 & 3
The mesosphere is the third layer of Earth's atmosphere, located between the stratosphere and the thermosphere.
Statement 1: The mesosphere ends at the mesopause, around 80 km altitude.
This statement is correct. The mesosphere extends from about 50 km to 80-85 km above Earth's surface. The upper boundary of the mesosphere is called the mesopause, which occurs at approximately 80 km altitude.
Statement 2: The temperature in the mesosphere increases with height.
This statement is incorrect. In the mesosphere, temperature actually decreases with increasing altitude. This is the opposite of what happens in the stratosphere above it. The temperature drops from about -3°C at the bottom of the mesosphere to as low as -90°C at the mesopause.
Statement 3: The mesosphere is the coldest layer of the atmosphere.
This statement is correct. The mesosphere contains the coldest temperatures in the entire atmosphere, with temperatures reaching as low as -90°C (-130°F) at the mesopause. This makes it colder than any other atmospheric layer.