<span>cesium sulfide IS THE NAME OF THAT COMPOUND</span>
The answer is; C
Conservation of matter in a reaction means that the mass of matter in the products is equal to the mass of the reactants. Energy/matter cannot be created or destroyed but converted from one form to another.
An expanding balloon with the increased evolution of gas is a good visible practical sign in the experiment on the conservation of matter in the reaction. As the magnesium disappears with an increased input of hydrochloric acid, the balloon gets bigger showing that more hydrogen is evolved from the reaction;
2HCL + Mg MgCl2 + H2
