1.What do you call the number in front of a chemical formula that tells how many atoms or molecules of a substance take part in the reaction? A) yield

B) coefficient

C) symbol

D) subscript

2.A balanced equation has ?

A) the same number of reactants as products

B) the same total number of coefficients on both sides of the equation

C) the same number of each kind of atom on both sides of the equation

D) an equal number of molecules on both sides of the equation

3.In a chemical reaction, the total mass of the products .

A) must always be the same as the total mass of the reactants

B) is always less than the total mass of the reactants in an open system

C) can be greater or less than the total mass of the reactants

D) must be less than the total mass of the reactants

4.Due to the principle of conservation of mass, .

A) all chemical formulas have coefficients

B) all chemical reactions must have an equal number of reactants and products.

C) all chemical reactions must take place in open systems

D) all chemical equations must be balanced

help me please