what must happen before a chemical reaction can begin?
the activation energy must be exceeded.
the activation energy must be reached.
the concentrations of products and reactants must be equal.
the concentration of reactant molecules must be reduced

B

Explanation:

I just took the test and got it right

answer: zinc is the substance which has a volume of 1.38 .

density is defined as the mass of an object per unit volume.

it can be calculated by dividing mass of a substance by its volume i.e.

si unit of density is kg per cubic meter and cgs unit of the same is gram per cubic centimeter.

now from the given data volume can be calculated by the formula .

hence, the volume of aluminium will be = which comes out to be 1.703 .

similarly, volume of zinc, chromium, and nickel will be 1.378 , 0.869 , and 0.356 respectively.