The diameter of a ping pong ball is 4.0cm. find the length in kilometers of a row of 6.02*1023 ping pong balls.

Let ping pong ball be called PPB

To solve this problem you must know the following unit change

1km = 1000m

1m = 100cm

Then, applying the change of units, we have that the length in kilometers is:

6.02x10 ^ 23PPB x 4.0cm / 1PPB x 1m / 100cm x 1km / 1000m = 2.41 x 10 ^ 19 km

The length is determined by multiplying the number of balls with the diameter. The answer that would come out of this is in units of centimeters.

L = (6.02 x 10^23 balls) (4 cm/ball)

L = 2.408 x 10^24 cm

Then, we use the proper conversion factor to convert centimeter to kilometer.

L = (2.408 x 10^24 cm) (1 m/100 cm) (1 km/1000 m)

L = (2.408 x 10^24) (10^5)

The answer to this item is 2.408 x 10^19 km.