What is the law of conservation of mass? A. The total mass of materials present after a chemical reaction is the same as the total mass present before the reaction.
B. In a given compound, the relative numbers and kinds of atoms are constant
C. If two elements A and B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers.
D. Each element is composed of extremely small particles called atoms.

A. The total mass of materials present after a chemical reaction is the same as the total mass present before the reaction.

Explanation:

Law of conservation states that whatever mass you start with you will end with, mass cannot be gained or lost

the answer is barium and copper bromide

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them