Question 1

What type of chemical reaction occurs when two or more substances combine to form a single new substance?

Accepted Answer

Combination reaction. A combination reaction involves multiple reactants joining to create one product. This process is also known as a synthesis reaction in many chemistry contexts. An example is the burning of magnesium in oxygen to form magnesium oxide.

Question 2

Which of the following is an example of an exothermic reaction?

Accepted Answer

Respiration. Respiration is an exothermic process because it releases energy for the body's use. It involves the breakdown of glucose in the presence of oxygen. Most combustion reactions are also classified as exothermic.

Question 3

What is the term for a reaction where a more reactive element takes the place of a less reactive element in a compound?

Accepted Answer

Displacement reaction. In a displacement reaction, a highly reactive metal replaces a lower reactivity metal from its salt solution. This follows the order of the reactivity series of metals. Iron reacting with copper sulfate is a classic example of this phenomenon.

Question 4

In a redox reaction, what happens to the substance that undergoes reduction?

Accepted Answer

It gains electrons. Reduction is defined as the gain of electrons by a chemical species. Conversely, oxidation involves the loss of electrons during the reaction. Both processes occur simultaneously in a single redox reaction.

Question 5

What gas is evolved when a dilute acid reacts with a metal like Zinc?

Accepted Answer

Hydrogen. Metals react with dilute acids to produce a salt and hydrogen gas. The presence of this gas can be tested using a burning matchstick which produces a pop sound. This is a common property of most active metals.

Chemical Reactions — Set 1