What should be the ratio between K2CO3 and H2O?
Normally when talking about ratios we would be talking the context of a chemical equation and ratios of the products and reactants. Here we do not have an equation but merely two listed chemicals that could be mixted together. Generally speaking, ratios of chemicals to one another are denoted by the leading numerical coefficients for each chemical. In this case the coefficients for both H2O and K2CO3 in this case are both 1, so we can imply that the ration between the two chemicals is 1:1 (read as one to one). In other words, for every molecule of H2O we have one molecule of K2CO3.