If $r$ denotes the distance between the sun and the earth, then the angular momentum of the earth around the sun is proportional to

Every planet revolves around the sun in an elliptical orbit :

$A.$ The force acting on a planet is inversely proportional to square of distance from sun.

$B.$ Force acting on planet is inversely proportional to product of the masses of the planet and the sun

$C.$ The centripetal force acting on the planet is directed away from the sun.

$D.$ The square of time period of revolution of planet around sun is directly proportional to cube of semi-major axis of elliptical orbit.

Choose the correct answer from the options given below :

If the earth is at one-fourth of its present distance from the sun, the duration of the year will be

A satellite revolving around a planet in stationary orbit has time period 6 hours. The mass of planet is one-fourth the mass of earth. The radius orbit of planet is : (Given $=$ Radius of geo-stationary orbit for earth is $4.2 \times 10^4 \mathrm{~km}$ )

A satellite is in a circular equatorial orbit of radius $7000\,km$ around the Earth. If it is transferred to a circular orbit of double the radius then its angular momentum will be