$$6 \times 2 + 6 \times 1 = 12 + 6 = 18$$ oxygen atoms

Question 1

Which of the following statements best describes an isotope of an element?

Accepted Answer

An atom with the same number of protons but a different number of neutrons.

Question 2

A neutral atom of sulfur has an atomic number of 16 and an atomic mass of 32. How many neutrons does it have?

Accepted Answer

$$32 - 16 = 16$$ neutrons

Question 3

Which of the following best explains why water is considered a polar molecule?

Accepted Answer

Oxygen has a stronger pull on electrons, creating a partial negative charge on the oxygen and a partial positive charge on the hydrogens.

Question 4

What is the electron configuration for a neutral atom with 10 electrons, and is it stable?

Accepted Answer

2 electrons in the first energy level, 8 in the second; it is stable because the outer shell is full.

Question 5

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed when two atoms share electrons.

Question 6

If a sodium atom (Na) loses one electron, what is the resulting charge and why?

Accepted Answer

It becomes $$\mathrm{Na}^+$$ because it has one more proton than electron.

Question 7

Which property of water allows it to moderate temperature in living organisms?

Accepted Answer

High specific heat capacity due to hydrogen bonding.

Question 8

A solution is made by dissolving table salt (NaCl) in water. In this solution, what is the solute and what is the solvent?

Accepted Answer

NaCl is the solute; water is the solvent.

Question 9

Which of the following best describes the role of hydrogen bonds in water?

Accepted Answer

They hold water molecules together, contributing to cohesion and high specific heat.

Question 10

A chemical equation is written as $$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2. $$How many oxygen atoms are present among the reactants?

Accepted Answer

$$6 	imes 2 + 6 	imes 1 = 12 + 6 = 18$$ oxygen atoms

Question 11

Which of the following is true about ions?

Accepted Answer

Ions are atoms or molecules that have gained or lost electrons, resulting in a net charge.

Question 12

Which of the following best explains why water forms a meniscus in a graduated cylinder?

Accepted Answer

Adhesion between water molecules and the glass causes the meniscus.

Question 13

A molecule of carbon dioxide ($$CO_2) $$contains which types of bonds?

Accepted Answer

Covalent bonds between carbon and oxygen atoms.

Question 14

Which of the following best describes a compound?

Accepted Answer

A substance made of two or more different elements bonded together.

Question 15

If a solution has a pH of 3, which of the following is true?

Accepted Answer

It has a high concentration of $$H^+$$ ions and is acidic.

Question 16

Which of the following is a real-life example of evaporative cooling due to water's properties?

Accepted Answer

Sweating in humans, where water absorbs heat as it evaporates from the skin.

Question 17

Which of the following best explains why water is called a 'universal solvent'?

Accepted Answer

Its polarity allows it to dissolve many ionic and polar substances.

Question 18

A neutral atom of carbon has an atomic number of 6 and an atomic mass of 12. How many electrons does it have?

Accepted Answer

6 electrons

Question 19

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule is a group of atoms held together by covalent bonds, while a compound is made of two or more different elements bonded together.

Question 20

Which of the following is a correct statement about the arrangement of electrons in energy levels for a stable atom with 16 electrons?

Accepted Answer

2 electrons in the first level, 8 in the second, and 6 in the third; it is not stable because the outer shell is not full.

Basic Chemistry Concepts for General Chemistry

Study Guide - Practice Questions