Question

In which of the following, ionised gases are the main constituents?

• A. Troposphere
• B. Thermosphere
• C. Stratosphere
• D. Mesosphere

Answer 1

Answer: (B)

The correct option is D Thermosphere
The thermosphere is the layer of the Earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation (UV) causes ionization. The thermosphere begins about 85 kilometres above the Earth. At these high altitudes, the residual atmospheric gases sort into strata according to molecular mass. Thermospheric temperatures increase with altitude due to the absorption of highly energetic solar radiation.

The region of thermosphere between the altitudes of 50 km and 100 km is called the ionosphere. In this region, there are high concentrations of ions like Oi, 0+, NO+ and electrons

Hence, the correct option is $\text{D}$