How many li atoms are in 4.5 moles of li?

The solution to this problem is actually very, very simple.

To find the number of atoms in a given number of moles, we simply multiply by Avogadro's constant.

The value of Avogadro's constant is 6.022 x 10²³

Number of Li atoms = moles x Avogadro's constant

Number of Li atoms = 4.5 x 6.022 x 10²³

Number of Li atoms = 2.7099 x 10²⁴

Number of Li atoms = 2.71 x 

Light year is a unit of measurement of distance (for space objects like satellites, stars etc)

It is defined as the distance traveled by a light in one year

The speed of light is 3 X 10^8 m / s

So it travels 3 X 10^8 meters in one second

The seconds in one year = 365 X 24 X 60 X 60 seconds

So distance traveled by light in one year

                               = 3 X 10^8 X  365 X 24 X 60 X 60 seconds

                               = 9,460,000,000,000,000 meters.

                                = 9.46 trillion kilometers

So the correct answers are

the distance that light travels in a year

9.46 trillion kilometers (5.88 trillion miles)