the number of protons in an element is represented by which number

HESI A2

Chemistry HESI A2 Quizlet

1. Which number represents the number of protons in an element?

A. Atomic mass
B. Mass number
C. Atomic number
D. Proton number

Correct answer: C

Rationale: The correct answer is C: Atomic number. The atomic number corresponds to the number of protons in an element. Protons are positively charged subatomic particles found in the nucleus of an atom. Each element has a unique atomic number, which defines its identity based on the number of protons it contains. Choice A, Atomic mass, is incorrect as it refers to the average mass of an atom of an element. Choice B, Mass number, represents the total number of protons and neutrons in an atom's nucleus. Choice D, Proton number, is not a commonly used term in chemistry to indicate the number of protons.

2. In a class of 28 people, there are 12 men and 16 women. What is the ratio of men to women?

A. 3:4
B. 4:7
C. 12:16
D. 1:2

Correct answer: A

Rationale: The correct ratio of men to women is 3:4. To find the ratio, divide the number of men by the number of women: 12 men / 16 women = 3/4, which simplifies to 3:4. Therefore, in a class of 28 people with 12 men and 16 women, the ratio of men to women is 3:4. Choice B (4:7) is incorrect because it does not accurately reflect the given numbers of men and women in the class. Choice C (12:16) is incorrect as it represents the actual count of men and women, not the ratio. Choice D (1:2) is incorrect as it does not match the proportion of men to women in the class.

3. In what type of covalent compounds are dispersion forces typically found?

A. Polar
B. Non-polar
C. Ionic
D. Hydrogen

Correct answer: B

Rationale: Dispersion forces, also known as London dispersion forces, are the weakest intermolecular forces that occur in non-polar covalent compounds. These forces result from temporary shifts in electron density within molecules, creating temporary dipoles. As a result, non-polar molecules, which lack a permanent dipole moment, can experience these dispersion forces. Polar compounds exhibit stronger intermolecular forces such as dipole-dipole interactions or hydrogen bonding, while ionic compounds involve electrostatic interactions between ions. Therefore, the correct answer is non-polar (choice B). Choices A, C, and D are incorrect because dispersion forces are typically found in non-polar covalent compounds, not polar, ionic, or hydrogen-bonded compounds.

4. Select the meaning of the underlined word in the following sentence. The patient will need to undergo additional testing.

A. Fail
B. Offer
C. Experience
D. Succumb

Correct answer: C

Rationale: In this context, the word 'undergo' means to experience or go through a process. When someone undergoes something, it implies they are subjected to it or experiencing it. Therefore, in the sentence provided, 'experience' is the correct meaning. Choices A, B, and D are incorrect as they do not align with the idea of going through a process or experiencing something.

5. Lulu is 5 years younger than her sister, who is 7 years older than their 15-year-old cousin. How old is Lulu?

A. 27
B. 22
C. 19
D. 17

Correct answer: C

Rationale: Let Lulu's sister's age be x. According to the given information, x = 15 (cousin's age) + 7 = 22. So, Lulu's sister is 22 years old. Since Lulu is 5 years younger than her sister, Lulu's age is 22 - 5 = 17. Therefore, Lulu is 17 years old. Choices A, B, and D are incorrect because they do not correspond to the calculations based on the information provided in the question.