NEX Basic Chemistry: Atomic Structure and Chemical Reactions 2

Question 1

How many electrons can the second energy level (shell) of an atom hold?

Accepted Answer

8

Answer

The second electron shell can hold a maximum of 8 electrons, following the formula 2n² where n is the shell number (2 x 2² = 8).

Question 2

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Answer

Covalent bonds form when two atoms share one or more pairs of electrons to achieve stable electron configurations.

Question 3

What is the pH of a neutral solution at 25°C?

Accepted Answer

7

Answer

A neutral solution has a pH of 7, where the concentration of hydrogen ions equals the concentration of hydroxide ions.

Question 4

In a chemical equation, what does a catalyst do?

Accepted Answer

Speeds up the reaction without being consumed

Answer

A catalyst increases the rate of a chemical reaction by lowering the activation energy without being consumed or permanently altered in the process.

Question 5

Which of the following is an example of a decomposition reaction?

Accepted Answer

2H₂O → 2H₂ + O₂

Answer

The breakdown of water into hydrogen and oxygen is a decomposition reaction because a single compound breaks down into two or more simpler substances.

(NEX) Nursing Entrance Exam Practice Test

(NEX) Nursing Entrance Exam Practice Test

NEX Basic Chemistry: Atomic Structure and Chemical Reactions 2