If 3.64g of sand is separated from 5.25g of a mixture of salt and sand what is the percentage of sand in the sample

Total weight of the mixture of sand and salt = 5.25 g
Weight of sand separated = 3.64 g
Weight of the salt in the mixture = (5.25 - 3.64) g
                                                   = 1.61 g
Then the percentage of sand in the sample = [(3.64/5.25) * 100] percent
                                                                      = 69.33%
So the percentage of sand in the total mixture of sand and salt is 69.33%.

The answer this would be radiative zone

The answer is a. that is an exothermic reaction which means it produces heat