What generally happens to the temperature of substances during a chemical reaction?

• It can either increase or decrease.

• It always decreases.

• It always increases.

• It remains constant.

What is an exothermic reaction?

• A reaction that neither absorbs nor releases energy.

• A reaction that only occurs at low temperatures.

• A reaction that absorbs energy in the form of heat.

• A reaction that releases energy in the form of heat.

What happens to the temperature in an endothermic reaction?

• It increases.

• It decreases.

• It remains the same.

• It fluctuates.

What is the term used to describe the calorific content of substances?

• Enthalpy

• Calorimetry

• Entropy

• Calorific value

How is the change in enthalpy symbolized?

• ΔH

• ΔE

• ΔT

• ΔC

What does a positive ΔH indicate in a chemical reaction?

• The reaction is exothermic.

• The reaction is endothermic.

• The reaction releases light.

• The reaction does not involve heat.

What is the difference between the enthalpy of products and reactants called?

• Calorific value

• Entropy

• Enthalpy change

• Heat capacity

In an exothermic reaction, what is the sign of ΔH?

• Zero

• Undefined

• Positive

• Negative