The hottest planet of the solar system is

The magnitudes of two stars $A$ and $B$ are $2.5$ and $-5$ respectively. The brightness ratio of $\frac{B}{A}$ is

According to the pulsating theory,the expansion and contraction of the universe repeats after every

$A$ galaxy is observed to be moving with a velocity of $8600 \ km \ s^{-1}$. If it is at a distance of $430$ million light-years from us,the Hubble constant and the corresponding age of the universe are respectively:

Hubble's law states that the velocity with which a galaxy is moving away from the Earth is proportional to:

The temperature of the Earth without the greenhouse effect would be: (in $^{\circ} C$)