Chemistry Test Chemical Reactions 2

Question 1

What type of reaction occurs when iron rusts in the presence of oxygen and water?

Accepted Answer

Oxidation-reduction

Answer

Rusting is an oxidation-reduction (redox) reaction where iron loses electrons to oxygen, forming iron oxide.

Question 2

In the reaction 2H₂O₂ → 2H₂O + O₂, what is the role of MnO₂ if added?

Accepted Answer

Catalyst

Answer

MnO₂ acts as a catalyst, speeding up the decomposition of hydrogen peroxide without being consumed.

Question 3

Which of the following is an example of a synthesis (combination) reaction?

Accepted Answer

2Na + Cl₂ → 2NaCl

Answer

2Na + Cl₂ → 2NaCl is a synthesis reaction because two elements combine to form a single compound.

Question 4

What happens to the rate of a chemical reaction when the temperature is increased?

Accepted Answer

It increases because molecules collide more frequently and with more energy

Answer

Higher temperature gives molecules more kinetic energy, increasing both collision frequency and the fraction of collisions with sufficient energy to react.

Question 5

In a single displacement reaction, which species is replaced?

Accepted Answer

A less reactive element is displaced by a more reactive one

Answer

In single displacement, a more reactive element displaces a less reactive element from its compound.

Chemistry Practice Test

Chemistry Practice Test

Chemistry Test Chemical Reactions 2