Two satellites of masses $m$ and $4m$ are revolving in the same orbit around the Earth. Which one of the following statements is correct?

The maximum and minimum distances of a comet from the Sun are $1.6 \times 10^{12} \ m$ and $8.0 \times 10^{10} \ m$ respectively. If the speed of the comet at the nearest point is $6 \times 10^{4} \ m/s$,the speed at the farthest point is ......... $\times 10^{3} \ m/s$.

The radii of circular orbits of two satellites $A$ and $B$ of the earth are $4R$ and $R,$ respectively. If the speed of satellite $A$ is $3V,$ then the speed of satellite $B$ will be ...... $V$.

The rotation period of an earth satellite close to the surface of the earth is $83$ minutes. The time period of another earth satellite in an orbit at a distance of three earth radii from its surface will be .......... $\min$

If a satellite has to orbit the earth in a circular path every $6 \text{ hrs}$, at what distance from the surface of the earth should the satellite be placed (in $\text{ km}$)? (Radius of earth $R_e = 6400 \text{ km}$)
(Assume $\frac{GM}{4\pi^2} = 8 \times 10^{12} \text{ m}^3\text{s}^{-2}$, where $G$ and $M$ are the gravitational constant and mass of earth, and $10^{1/3} = 2.1$)

Why can the entire surface of the Earth be viewed with the help of a polar satellite?