Question

The main components in mesosphere are:
(A). ${O_{2{\text{ }}}}\operatorname{and} {\text{ }}{{\text{N}}_2}$
(B). ${O_2}{\text{ }}\operatorname{and} {N_2}$
(C). $N{O^ + }{\text{ }}\operatorname{and} {\text{ }}{O^ + }$
(D). ${N_2}{\text{ }}\operatorname{and} {\text{ }}{O_3}$

Answer 1

The atmosphere is a mixture of gases that surrounds the Earth and protects it from the dangerous ray of the sun. The atmosphere is divided into five layers that are troposphere, stratosphere, mesosphere, thermosphere and exosphere. These layers are divided depending upon the temperature change with respect to height.

Complete step by step answer:
The mesosphere is the third layer of atmosphere that lies between the stratosphere and thermosphere, in mesosphere also, the temperature. As similar to the troposphere, in the mesosphere also, the temperature gets reduced with the increase in height. It is the coldest part of the Earth’s atmosphere with the temperature below than $- 143^\circ C$ . The mesosphere gets started from an height of $50{\text{ }}\operatorname{to} {\text{ 56 Km}}$ above the earth’s surface and its upper boundary is usually around$85{\text{ to 100 Km}}$ . The altitude of these upper and lower boundaries of the mesosphere do vary with the change in latitude.
The transition between mesosphere and the thermosphere is called mesopause and is the altitude at which the temperature reaches a minimum before increasing again with the height of the thermosphere (it is the atmosphere layer which is situated above the mesosphere.). The mesosphere is dispersed with the D-region ionosphere, the lowest portion of the partially ionized plasma layer that surrounds the Earth. It is an intense radar scattering layer and does cause atmospheric motions which are dominated by gravity vows and tides. These changes are more clearly visible at the polar mesosphere.
The mesosphere contains about $0.1$ percent of air mass over the Earth. Along with dry, ${H_2}O$ has also been observed with a mixing ratio of seven parts per million $\left( {ppm} \right)$. The number of chemicals with significant mixing ratios are much smaller than in the troposphere because of the dynamic blocking by the stratosphere. Major photochemical species are found to occupy major features of photochemistry there like $O_2^ +$ and$N{O^ + }$. Also, the ions are effectively produced above the mesosphere due to sunlight.

So, the correct answer is Option C.

Note: Within the mesosphere, the temperature reduces with increases in height because of decreasing absorption of solar radiation and also due to the increasing cooling by $C{O_2}$ radiative emission. Thus, the mesosphere is the coldest part of the atmosphere, especially the mesopause( that is the top of the mesosphere).