if gas a has four times the molar mass of gas b you would expect it to diffuse through a plug

HESI A2

Chemistry HESI A2 Practice Test

1. If gas A has four times the molar mass of gas B, you would expect it to diffuse through a plug ___________.

A. at half the rate of gas B
B. at twice the rate of gas B
C. at a quarter the rate of gas B
D. at four times the rate of gas B

Correct answer: A

Rationale: When comparing the diffusion rates of two gases, according to Graham's law of diffusion, the rate of diffusion is inversely proportional to the square root of the molar mass. If gas A has four times the molar mass of gas B, the square root of the molar masses ratio (4:1) is 2. This means that gas A would diffuse through a plug at half the rate of gas B. Therefore, the correct answer is A, at half the rate of gas B. Choices B, C, and D are incorrect because they do not reflect the correct relationship between the molar masses and the rates of diffusion according to Graham's law.

2. When balanced, the reaction Fe + Oâ‚‚ â†’ FeO will be?

A. 2Fe + 2Oâ‚‚ â†’ 3FeO
B. 4Fe + 6Oâ‚‚ â†’ 6FeO
C. 2Fe + 3Oâ‚‚ â†’ 2FeO
D. 4Fe + 3Oâ‚‚ â†’ 2FeO

Correct answer: C

Rationale: To balance the chemical equation Fe + Oâ‚‚ â†’ FeO, the coefficients needed are 2 for Fe and 1 for O. Therefore, the balanced equation becomes 2Fe + Oâ‚‚ â†’ 2FeO, which translates into 2Fe + 3Oâ‚‚ â†’ 2FeO. This corresponds to option C. Choice A has the incorrect number of oxygen molecules. Choice B has an incorrect number of Fe atoms on the product side. Choice D also has an incorrect number of Fe atoms on the product side.

3. What type of radiation is high-energy electromagnetic radiation that lacks charge and mass?

A. Beta
B. Alpha
C. Gamma
D. Delta

Correct answer: C

Rationale: Gamma radiation is a form of high-energy electromagnetic radiation that does not possess charge or mass. This type of radiation is commonly used in various fields due to its penetrating ability and lack of charge or mass, making it different from alpha and beta radiation, which consist of charged particles. Therefore, the correct answer is C - Gamma. Choices A and B are incorrect as they refer to alpha and beta radiation, which are composed of charged particles. Choice D, Delta, is not a type of radiation.

4. What are neutral particles called?

A. Neutrons
B. Protons
C. Electrons
D. Cations

Correct answer: A

Rationale: Neutral particles, which have no electric charge, are known as neutrons. Neutrons are found in the nucleus of an atom along with protons. Electrons carry a negative charge and orbit the nucleus. Cations are positively charged ions formed by losing electrons. Therefore, the correct answer is 'Neutrons' as they are the neutral particles in an atom, unlike protons, electrons, or cations.

5. What are the three types of radiation?

A. Alpha, beta, gamma
B. Alpha, beta, delta
C. Gamma, delta, epsilon
D. Beta, gamma, epsilon

Correct answer: A

Rationale: The correct answer is Alpha, beta, gamma. Alpha radiation consists of helium nuclei, beta radiation comprises electrons or positrons, and gamma radiation is high-energy electromagnetic radiation. Choice B, delta, is incorrect as delta is not a type of radiation. Choice C, gamma, delta, epsilon, and Choice D, beta, gamma, epsilon, are incorrect as they do not include the three standard types of radiation.