(07.01 LC) Which of the following happens during an exothermic chemical change? (4 points)
Net energy increases.
Heat is absorbed.
Net energy remains constant.
Heat is released.

Heat is released.

Explanation:

Exothermic reactions are reactions that give off radiant heat when you come in close contact with them.

heat is released

Explanation:

there is a release of energy to the surroundings resulting in a net decrease

b is the correct

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2