If distance between earth and sun become four times, then time period becomes
a)	4 times	b)	8 times	c)	1/4  times	d)	1/8 times

(b)

According to Kelper’s third law (law of periods),

where T  is time taken by the planet to go once around the sun and R is semi-major axis (distance) of the elliptical orbit.

(i)

Where  is constant of proportionality.

When  becomes 4 times let time period be .

So, time period becomes 8 times of previous value.