Which of these would increase the heat generated and reduce the time it takes the ice cube to melt? 1.Increasing the size of the ice cube to be melted.

2.Increasing the amount of calcium chloride placed in the bag.

3.Increasing the size of the plastic bag.

4.Dropping the ice cube in the bag with the calcium chloride and water and then shaking the bag.

5.Putting more water and less calcium chloride in the bag.

6.Doubling the size of the plastic bag and doubling the amount of water and calcium chloride used.

answer: - first one is the correct answer. .

explanations: - potassium sulfide is and cobalt(ii) chloride is .

charge on k is +1, charge on s is -2, charge on co is +2 and charge on cl is -1.

in a double replacement reaction the ion exchange takes place. in general the reaction looks like:

if one of the product is insoluble as per solubility rules then a precipitate of it is formed.

when we mix the aqueous solutions of potassium sulfide and cobalt(ii) chloride then chloride ion goes with potassium ion and sulfide ion goes with cobalt ion and the balanced equation is written as:

k and cl has equal charges, similarly co and s has equal charges and hence no subscripts are used for the product side.

as per the solubility rules, cos is insoluble and so it's precipitate is formed.

looking at the given choices, first choice is correct.