Question 1

Which of the following statements best explains why sodium (Na) forms a cation when it reacts with chlorine (Cl) to form table salt (NaCl)?
Correct answer: Sodium loses an electron, resulting in a net positive charge.

Accepted Answer

Sodium loses an electron, resulting in a net positive charge.

Question 2

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

Accepted Answer

6

Question 3

Which property of water allows it to moderate Earth's climate by absorbing large amounts of heat with only small changes in temperature?
Correct answer: High specific heat capacity

Accepted Answer

High specific heat capacity

Question 4

Which of the following best describes an isotope?
Correct answer: An atom with the same number of protons but a different number of neutrons

Accepted Answer

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

Question 5

A solution has a pH of 3. Which of the following statements is true about this solution?
Correct answer: It is acidic and has a high concentration of H+ ions.

Accepted Answer

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

Question 6

Which of the following best explains why water forms a meniscus in a glass graduated cylinder?
Correct answer: Water molecules are attracted to the glass due to adhesion.

Accepted Answer

Water molecules are attracted to the glass due to adhesion.

Question 7

Which of the following is a correct electron configuration for a neutral oxygen atom (atomic number 8)?
Correct answer: 2, 6

Accepted Answer

2, 6

Question 8

In the chemical equation for photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, what does the coefficient '6' in front of CO₂ indicate?
Correct answer: Six molecules of carbon dioxide are involved in the reaction.

Accepted Answer

Six molecules of carbon dioxide are involved in the reaction.

Question 9

Which type of bond is primarily responsible for holding together the two hydrogen atoms and one oxygen atom in a single water molecule?
Correct answer: Polar covalent bond

Accepted Answer

Polar covalent bond

Question 10

A patient is given an intravenous solution with a pH of 9. What effect does this solution have on the concentration of ions in the patient's blood?
Correct answer: It increases the concentration of OH- ions.

Accepted Answer

It increases the concentration of OH- ions.

Question 11

Which of the following best explains why table salt (NaCl) dissolves easily in water?
Correct answer: Water's polarity allows it to surround and separate Na+ and Cl- ions.

Accepted Answer

Water's polarity allows it to surround and separate Na+ and Cl- ions.

Question 12

Which of the following changes when an atom forms an ion?
Correct answer: The number of electrons

Accepted Answer

The number of electrons

Question 13

Which of the following is an example of a hydrogen bond?
Correct answer: The attraction between a hydrogen atom in one water molecule and an oxygen atom in another water molecule

Accepted Answer

The attraction between a hydrogen atom in one water molecule and an oxygen atom in another water molecule

Question 14

A scientist discovers a new element with an atomic number of 115 and a mass number of 290. How many neutrons does this element have?
Correct answer: 175

Accepted Answer

175

Question 15

Which of the following best describes the difference between a covalent bond and an ionic bond?
Correct answer: Covalent bonds involve sharing electrons; ionic bonds involve the transfer of electrons.

Accepted Answer

Covalent bonds involve sharing electrons; ionic bonds involve the transfer of electrons.

Question 16

Which of the following scenarios best illustrates the concept of cohesion in water?
Correct answer: Water droplets forming beads on a waxed car hood.

Accepted Answer

Water droplets forming beads on a waxed car hood.

Question 17

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic mass?
Correct answer: 35

Accepted Answer

35

Question 18

Which of the following best explains why noble gases (like neon and argon) are chemically unreactive?
Correct answer: They have a full outer energy level of electrons.

Accepted Answer

They have a full outer energy level of electrons.

Question 19

A student mixes hydrochloric acid (HCl) with water. What happens to the pH of the solution and why?
Correct answer: The pH decreases because HCl increases the concentration of H+ ions.

Accepted Answer

The pH decreases because HCl increases the concentration of H+ ions.

Question 20

Which of the following best describes the role of subscripts in a chemical formula?
Correct answer: They indicate the number of atoms of each element in a molecule.

Accepted Answer

They indicate the number of atoms of each element in a molecule.

C1

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