Nursing Elites

1. How many grams of solid CaCO3 are needed to make 600 mL of a 0.35 M solution? The atomic masses for the elements are as follows: Ca = 40.07 g/mol; C = 12.01 g/mol; O = 15.99 g/mol.

• A. 18.3 g
• B. 19.7 g
• C. 21.0 g
• D. 24.2 g

Correct answer: B

Rationale: To calculate the grams of solid CaCO3 needed for a 0.35 M solution, we first find the molar mass of CaCO3: Ca = 40.07 g/mol, C = 12.01 g/mol, O = 15.99 g/mol. The molar mass of CaCO3 is 40.07 + 12.01 + (3 * 15.99) = 100.08 g/mol. The molarity formula is Molarity (M) = moles of solute / liters of solution. Since we have 0.35 moles/L and 600 mL = 0.6 L, we have 0.35 mol/L * 0.6 L = 0.21 moles of CaCO3 needed. Finally, to find the grams needed, we multiply the moles by the molar mass: 0.21 moles * 100.08 g/mol = 21.01 g, which rounds to 19.7 g. Therefore, 19.7 grams of solid CaCO3 are needed to make 600 mL of a 0.35 M solution. Choice A (18.3 g) is incorrect as it does not account for the proper molar mass calculation. Choice C (21.0 g) and Choice D (24.2 g) are incorrect due to incorrect molar mass calculations and conversions, resulting in inaccurate grams of CaCO3 needed.

2. Which of the following are the products of anaerobic respiration in humans?

• A. Ethyl alcohol and CO2
• B. Ethyl alcohol only
• C. Lactic acid and CO2
• D. Lactic acid only

Correct answer: C

Rationale: During anaerobic respiration in humans, lactic acid and CO2 are produced. Choice A, 'Ethyl alcohol and CO2,' is incorrect because ethyl alcohol is not a product of anaerobic respiration in humans. Choice B, 'Ethyl alcohol only,' is incorrect as ethyl alcohol is not a product of anaerobic respiration in humans. Choice D, 'Lactic acid only,' is incorrect because CO2 is also a product of anaerobic respiration in humans.

3. What type of bond links amino acids together to form proteins?

• A. Hydrogen bond
• B. Ionic bond
• C. Disulfide bond
• D. Covalent bond

Correct answer: D

Rationale: Amino acids are linked together by covalent bonds to form proteins. Specifically, the bond that links amino acids together is called a peptide bond, which is a type of covalent bond. The peptide bond forms between the amino group of one amino acid and the carboxyl group of another amino acid, resulting in the formation of a peptide chain. While hydrogen bonds, ionic bonds, and disulfide bonds are important for protein structure and stability, the primary bond responsible for linking amino acids in a protein chain is the covalent peptide bond. Hydrogen bonds are involved in maintaining the secondary structure of proteins, such as alpha helices and beta sheets. Ionic bonds and disulfide bonds contribute to tertiary and quaternary structures of proteins by stabilizing interactions between different parts of the protein or between different protein subunits, respectively.

4. When testing how quickly a rat dies based on the amount of poison it eats, which of the following is the independent variable and which is the dependent variable?

• A. How quickly the rat dies is the independent variable; the amount of poison is the dependent variable.
• B. The amount of poison is the independent variable; how quickly the rat dies is the dependent variable.
• C. Whether the rat eats the poison is the independent variable; how quickly the rat dies is the dependent variable.
• D. The cage the rat is kept in is the independent variable; the amount of poison is the dependent variable.

Correct answer: B

Rationale: The correct answer is B. In this experiment, the independent variable is the amount of poison because it is what is being manipulated by the researcher. The dependent variable is how quickly the rat dies, as it is the outcome that is being measured based on the different amounts of poison administered. Choice A is incorrect because the independent variable should be what is being manipulated or changed, which is the amount of poison in this case. Choice C is incorrect because whether the rat eats the poison is not being varied or controlled by the researcher. Choice D is incorrect because the cage the rat is kept in is not relevant to the relationship being studied between the amount of poison and the rat's survival time.

5. What type of bond holds water molecules together?

• A. Covalent bond
• B. Hydrogen bond
• C. Ionic bond
• D. Peptide bond

Correct answer: B

Rationale: The correct answer is B: Hydrogen bond. Hydrogen bonds are responsible for holding water molecules together. In a water molecule, the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive, creating a partial positive and negative charge. This polarity allows hydrogen bonds to form between adjacent water molecules. Covalent bonds involve the sharing of electrons, ionic bonds involve transfer of electrons between ions, and peptide bonds are specific to linking amino acids in proteins, which are not relevant to water molecule interactions.

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