$$\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$$

Question 1

Which of the following best describes the difference in electron behavior between ionic and covalent bonds?

Accepted Answer

In ionic bonds, electrons are transferred from one atom to another; in covalent bonds, electrons are shared between atoms.

Question 2

An element has 11 protons and 12 neutrons. What is its atomic number?

Accepted Answer

$$11$$

Question 3

An element has 11 protons and 12 neutrons. What is its mass number?

Accepted Answer

$$23$$

Question 4

Why do noble gases (Group 18) rarely form chemical bonds with other elements?

Accepted Answer

They have a full valence shell, making them chemically stable.

Question 5

Balance the following chemical equation: $$H_2$$ + $$O_2$$ \rightarrow H_2O$$

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 6

A student tests a mystery liquid with a pH strip that turns bright red, indicating a pH of 2. What does this tell you about the substance?

Accepted Answer

It is a strong acid.

Question 7

Which of the following is a real-world example of an ionic compound?

Accepted Answer

Sodium chloride ($$NaCl)$$

Question 8

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms.

Question 9

A patient is given a solution with a pH of 2 to drink. What effect might this have on their body?

Accepted Answer

It could increase the acidity of their stomach, potentially causing harm.

Question 10

Which of the following best explains why sodium (Na) and chlorine (Cl) form an ionic bond?

Accepted Answer

Sodium donates an electron to chlorine, resulting in oppositely charged ions that attract.

Question 11

Which of the following is the correct formula for calculating the mass number of an atom?

Accepted Answer

$$	ext{Mass number} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 12

Which of the following best describes the electron configuration of a noble gas?

Accepted Answer

A noble gas has a full outermost electron shell.

Question 13

Which of the following substances is most likely to have a covalent bond?

Accepted Answer

Carbon dioxide ($$CO_2)$$

Question 14

If a chemical reaction is not balanced, which law is being violated?

Accepted Answer

Law of Conservation of Mass

Question 15

Which of the following best describes what happens to the electrons in a molecule of $$H_2O$$?

Accepted Answer

Electrons are shared between hydrogen and oxygen atoms.

Question 16

A solution has a pH of 7. Which of the following statements is true?

Accepted Answer

The solution is neutral.

Question 17

Which of the following is the correct balanced equation for the combustion of hydrogen gas in oxygen to form water?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 18

Which of the following best explains why hydrochloric acid ($$HCl) is $$considered a strong acid?

Accepted Answer

It completely dissociates in water, releasing $$H^+$$ ions.

Question 19

A chemist mixes equal volumes of a solution with pH 2 and a solution with pH 12. What is the expected pH of the resulting mixture?

Accepted Answer

Approximately pH 7 (neutral)

Question 20

Which of the following is a property of ionic compounds in the solid state?

Accepted Answer

They have high melting points and are brittle.

Step-by-Step Guidance: Atomic Structure, Bonding, and Chemical Properties

Guida di studio - Domande di pratica