For an opaque body,the coefficient of transmission is:

The coefficient of absorption $(a)$ and the coefficient of reflection $(r)$ of a thin uniform plate are $0.77$ and $0.17$ respectively. If $250 \ kcal$ of heat is incident on the surface of the plate,the quantity of heat transmitted $(t)$ is: (in $kcal$)

The following figure shows two air-filled bulbs connected by a $U$-tube partly filled with alcohol. One bulb is painted black and the other is painted white (or silver/shiny). What happens to the levels of alcohol in the limbs $X$ and $Y$ when an electric bulb placed midway between the two bulbs is lighted?

Surface temperature of the sun is of the order of $K$.

The following graph shows the correct variation in the intensity of heat radiations emitted by a black body with respect to frequency at different fixed temperatures. Identify the correct graph.

The black lines in the solar spectrum during a solar eclipse can be explained by