the answer to this question is B
Answer:
Explanation:
A light year is a unit of length and is defined as "the distance a photon would travel in vacuum during a Julian year at the speed of light at an infinite distance from any gravitational field or magnetic field. "
In other words: It is the distance that the light travels in a year.
This unit is equivalent to
, which mathematically is expressed as:

Doing the conversion:
This is the distance from Earth to Sirius in miles.
Answer:
<u>Very low</u>
<u>Explanation:</u>
It is fair to say to a reasonable extent that there are very low chances that radio transmissions from Earth or messages sent on distant space probes will ever be received by living beings
.
Bear in mind that for years some scientists have believed without any substantial evidence that there are other living beings in distant space.
C. The water cycle spreads water out evenly around the whole Earth
Answer:
Work done against gravity will be
W = Mgℓ
Explanation:
Work done to raise the mass from ground to given height is against gravity
So here work done is given by the formula

here we know that

it is the force due to gravity which is also known as weight
so here distance moved by the object is given as
d = ℓ
now work done is given as
W = Mg ℓ