Which graph best represents the variation of radius $r$ of a circular orbit of a satellite against its time period $T$?

$A$ planet of mass $m$ moves around the sun of mass $M$ in an elliptical orbit. The maximum and minimum distances of the planet from the sun are $r_1$ and $r_2$ respectively. The time period of the planet is proportional to ..........

Explain Kepler's first law (Law of Orbits) for planetary motion.

Suppose there existed a planet that went around the sun twice as fast as the earth. What would be its orbital size as compared to that of the earth?

$A$ star of mass $M$ (equal to the solar mass) with a planet (much smaller than the star) revolves around the star in a circular orbit. The velocity of the star with respect to the centre of mass of the star-planet system is shown below. The radius of the planet's orbit is closest to .......... $AU$ ($1 \, AU =$ Earth-Sun distance).

$A$ planet revolves around the sun whose mean distance is $1.588$ times the mean distance between the earth and the sun. The revolution time of the planet will be ........... $years$.