How do the products and reactants of a chemical change compare?
a) the mass of the products is greater than the mass of the reactants because energy is taken in by the reaction.
b) the mass of the products equals the mass of the reactants because the same matter is present.
c) the mass of the products equals the mass of the reactants because there is no energy involved in the reaction.
d) the mass of the products is less than the mass of the reactants because energy is given off by the reaction.

Of the groups of elements below, which are most likely to gain electrons to become anions? a. alkali metal b. boron group c. halogen d. transition metal

Liquid ammonia is produced at high temperatures and under great pressure in a tank by passing a mixture of nitrogen gas and hydrogen gas over an iron catalyst. the reaction is represented by the following equation. n2(g) + 3h2(g) → 2nh3(g) changing all but one experimental condition will affect the amount of ammonia produced. that condition is a) increasing the concentration of both reactants b) changing the temperature within the tank c) decreasing the pressure within the tank. d) increasing only the amount of nitrogen present.

How many moles of potassium are needed to react completely with 12.8 moles of magnessium bromide?