When 40.2g of kc103 is heated what quantity of kc1 is produced
Two points. The number 1 is not the letter l and you DON'T use lower case for all chemical symbols. Potassium chlorate is KClO3.
First write and balance the equation.
2KClO3 ==> 2KCl + 3O2
mols KClO3 = grams/molar mass = ?
Using the coefficients in the balanced equation, convert mols KClO3 to moles KCl.
Now convert mols KCl to grams. g = mols x molar mass.