Answer:
The simplest form ratio is 1 : 50000.
Explanation:
To find the ratio of 2 cm : 1 km
Firstly, we need to convert both the quantities into the same unit of measurement.
Now 1 km = 1,00,000 cm
So, now we need to find the ratio of 2 cm : 1,00,000 cm
⇒ The required Ratio is

Hence, the simplest form ratio is 1 : 50000