Here's how to determine the mole ratio of salt to water in Co(NO3)2.6H2O:

Understanding the Formula

* Co(NO3)2: This represents the salt, cobalt(II) nitrate.

* 6H2O: This represents six water molecules, indicating that the salt is hydrated.

Mole Ratio

The formula tells us that for every 1 mole of Co(NO3)2, there are 6 moles of water.

Therefore, the mole ratio of salt (Co(NO3)2) to water (H2O) is 1:6.