what is the charge of a gamma ray

HESI A2

Chemistry Hesi A2

1. What is the charge of a gamma ray?

A. -1
B. +1
C. +2
D. No charge

Correct answer: D

Rationale: Gamma rays are a form of electromagnetic radiation with no charge. They are neutral particles that do not possess any electric charge. This characteristic allows them to be unaffected by electric or magnetic fields. Additionally, gamma rays travel at the speed of light in a vacuum. Choices A, B, and C are incorrect as gamma rays do not carry a charge of -1, +1, or +2; they are neutral entities.

2. What is the process of breaking bonds and forming new bonds to create new chemical compounds?

A. Physical reaction
B. Chemical reaction
C. Nuclear reaction
D. Mechanical reaction

Correct answer: B

Rationale: A chemical reaction involves the breaking and forming of bonds to create new substances. During a chemical reaction, the original chemical bonds are broken, and new bonds are formed to produce one or more new substances with different properties from the reactants. This transformation is a fundamental concept in chemistry and distinguishes chemical reactions from physical, nuclear, or mechanical reactions. Choice A, 'Physical reaction,' does not involve the breaking and forming of chemical bonds but rather changes in physical state or appearance. Choice C, 'Nuclear reaction,' involves changes in the nuclei of atoms, not the breaking and forming of chemical bonds. Choice D, 'Mechanical reaction,' refers to reactions involving physical forces or movements, not the breaking and forming of chemical bonds as in a chemical reaction.

3. How many times more acidic is a substance with a pH of 3 compared to a substance with a pH of 5?

A. 8
B. 2
C. 100
D. 1,000

Correct answer: D

Rationale: The pH scale is logarithmic, indicating that each pH unit change reflects a 10-fold difference in acidity level. Going from pH 5 to pH 3 involves a difference of 2 units, which translates to a 100-fold increase in acidity level (10^2 = 100 for each unit). Therefore, a substance with a pH of 3 is 1,000 times more acidic than a substance with a pH of 5 (100 * 10 = 1,000). Choice A (8) is incorrect as it does not consider the logarithmic nature of the pH scale. Choice B (2) is incorrect because it represents the difference in pH units, not the increase in acidity level. Choice C (100) is incorrect as it miscalculates the increase in acidity level, which is 1,000 times and not 100 times.

4. What are the products of combustion of a hydrocarbon in excess oxygen?

A. Carbon dioxide and water
B. Naphthalene
C. Chlorine and bromine
D. Carbonium ions

Correct answer: A

Rationale: The correct answer is A: Carbon dioxide and water. During the combustion of a hydrocarbon in excess oxygen, the hydrocarbon reacts to produce carbon dioxide and water vapor as the final products. This reaction is known as complete combustion, where the hydrocarbon combines with oxygen to form carbon dioxide and water. Choices B, C, and D are incorrect because naphthalene is a specific hydrocarbon compound, chlorine and bromine are not typically formed during the combustion of hydrocarbons in excess oxygen, and carbonium ions are not the products of this reaction.

5. On the periodic table, where are atoms with the largest atomic radius located?

A. At the top of their group
B. In the middle of their group
C. At the bottom of their group
D. Along the right-hand side

Correct answer: C

Rationale: Atoms with the largest atomic radius are located at the bottom of their group on the periodic table. This is because atomic radius increases down a group due to the addition of more energy levels or shells of electrons. As you move down a group, the outermost electrons are further away from the nucleus, leading to an increase in atomic radius. Choice A 'At the top of their group' is incorrect because atomic radius decreases going up within a group. Choice B 'In the middle of their group' is incorrect as the atomic radius generally increases as you go down a group, not in the middle. Choice D 'Along the right-hand side' is incorrect because atomic radius tends to decrease from left to right across a period on the periodic table due to increased nuclear charge and effective nuclear charge.