you would expect an amino acid to contain which two functional groups

HESI A2

Chemistry HESI A2 Practice Test

1. Which two functional groups would you expect an amino acid to contain?

A. R-NH2 and R-COOH
B. R-CHO and R-CO-NH
C. R-OH and R-COOR
D. R-O-R and R-COOH

Correct answer: A

Rationale: Amino acids are organic compounds that are characterized by the presence of an amino group (NH2) and a carboxylic acid group (COOH) in their chemical structure. These two functional groups, found in option A, are fundamental components of amino acids and play crucial roles in their classification and biological functions. Option B contains an aldehyde group (CHO) and an amide group (CO-NH), which are not characteristic functional groups of amino acids. Option C includes a hydroxyl group (OH) and an ester group (COOR), which are not typically present in amino acids. Option D presents ether (R-O-R) and carboxylic acid (COOH) functional groups, which do not represent the functional groups commonly found in amino acids.

2. What is the oxidation state of the oxygen atom in the compound NaOH?

A. -2
B. -1
C. 0
D. +2

Correct answer: B

Rationale: In the compound NaOH (sodium hydroxide), the oxidation state of the sodium ion (Na) is +1 as it commonly has a +1 charge in ionic compounds. Oxygen (O) typically has an oxidation state of -2 in most compounds. Since the compound is electrically neutral and the overall charge is zero, the sum of the oxidation states of all atoms in the compound must be zero. Therefore, considering that sodium has an oxidation state of +1, the oxygen atom in NaOH must have an oxidation state of -1 to balance the charges and overall neutrality of the compound. Choice A (-2) is incorrect as this is not the oxidation state of oxygen in this compound. Choice C (0) is incorrect as oxygen in NaOH does not have an oxidation state of 0. Choice D (+2) is incorrect as oxygen typically has a negative oxidation state in compounds, not a positive one.

3. What type of chemical reaction involves the combination of two elements to form a product?

A. Decomposition
B. Combustion
C. Synthesis
D. Double replacement

Correct answer: C

Rationale: A synthesis reaction involves the combination of two or more substances to form a single, more complex product. In the context of chemical reactions, it specifically refers to the combination of two elements to form a compound. Therefore, the correct answer is C. Decomposition reactions involve the breakdown of a single compound into simpler substances (opposite of synthesis). Combustion reactions involve a substance reacting with oxygen to produce heat and light, not the combination of elements. Double replacement reactions involve the exchange of ions between two compounds, leading to the formation of two new compounds, not the combination of two elements.

4. What can stop the penetration of beta radiation particles?

A. Plastic
B. Glass
C. Aluminum foil
D. Concrete

Correct answer: C

Rationale: Beta radiation particles are high-energy, fast-moving electrons or positrons. Aluminum foil is effective in stopping beta radiation due to its ability to absorb and block these particles. When beta particles interact with the aluminum foil, they lose energy and are absorbed, preventing their penetration. Plastic and glass are not as effective as aluminum foil in stopping beta radiation. While concrete provides some shielding against beta particles, aluminum foil is a more suitable material for this purpose as it offers better absorption and blocking capabilities.

5. How many electrons are in a neutral atom of neon?

A. 9
B. 10
C. 11
D. 12

Correct answer: B

Rationale: The atomic number of neon is 10, which represents the number of protons in its nucleus. In a neutral atom, the number of electrons is equal to the number of protons to maintain electrical neutrality. Therefore, a neutral atom of neon contains 10 electrons, matching the 10 protons within the nucleus. Choice A (9 electrons) is incorrect as it doesn't correspond to the atomic number of neon. Choices C (11 electrons) and D (12 electrons) are also incorrect as they do not align with the correct atomic number of neon.