GSHS Year 9 chemistry exam

In an endothermic reaction, heat is ...

• absorbed

• released

Answer explanation

In an endothermic reaction, heat is absorbed.

In an exothermic reaction, heat is ...

• absorbed

• released

Answer explanation

In an exothermic reaction, heat is released.

6. Which of these processes is always exothermic?

• A. evaporation

• B. burning

• C. insulation

• D. melting

Answer explanation

The process of burning is always exothermic because it releases heat energy.

1. Equal amounts of four different substances (A-D) where added separately to equal amounts of an acid and a thermometer placed in the mixture. For which substance is the reaction the most exothermic?

Answer explanation

The reaction is most exothermic for substance D, as it causes the temperature to rise by 5°C.

If a chemical reaction is EXOTHERMIC, the temperature would....

• Stay the same

• Increase

• Decrease

Answer explanation

In an exothermic reaction, the temperature increases.

During an endothermic reaction in a beaker if we are part of the surroundings and touched the beaker, it would feel _______. 

• Warm

• Cold

Answer explanation

If we touch the beaker during an endothermic reaction, it would feel cold because the reaction absorbs heat from the surroundings.

What type of reaction is shown in the photo?

• Exothermic

• Isothermic

• Endothermic

• None of the  above

Answer explanation

The reaction shown in the photo is an exothermic reaction, as it releases heat energy.

Is photosenthysis an Exothermic or an Endothermic reaction?

• Endothermic

• Exothermic

Answer explanation

Photosynthesis is an endothermic reaction because it requires energy from the surroundings to convert sunlight into chemical energy.

What type of reaction occurs in a hand warmer?

• exothermic

• endothermic

Answer explanation

A hand warmer undergoes an exothermic reaction, releasing heat. This reaction occurs when the correct choice, 'exothermic,' is selected.

A student mixed two chemicals to allow them to react. The temperature before the reaction was 25 ° C. The temperature after the reaction was 18° C. Which of the following is true?

• It is an exothermic reaction

• It is an endothermic reaction

Answer explanation

The temperature decreased during the reaction, indicating an endothermic reaction.