To calculate how far light travels in a specific period of time, we need to know the speed at which light travels. Light travels at 299,792 kilometers per second.

Speed is a measure of the distance travelled per unit time. This is the equation for speed:

`speed = (distance)/(time)`

Using the equation for speed, we can obtain an equation for distance:

`distance = speed*time`

Since the speed of light is expressed in kilometers per second, first we must convert our time period to seconds, then multiply by the speed of light. There are 60 minutes in an hour and 60 seconds in each minute.

1 hour = 60 minutes = 60*60 seconds.

Using the distance formula, we find:

`distance = 299792*(2.0*10^1)*60*60=21585024000` km

which can be simplified to `2.18850*10^10 kilometers`

So, in two hours, light travels 2.18850X10^10 kilometers.

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