if 5 g of nacl 1 mole of nacl are dissolved in enough water to make 500 l of solution what is the molarity of the solution

HESI A2

Chemistry Hesi A2

1. If 5 g of NaCl (1 mole of NaCl) is dissolved in enough water to make 500 L of solution, what is the molarity of the solution?

A. 1.0 M
B. 2.0 M
C. 11.7 M
D. The answer cannot be determined from the information given.

Correct answer: C

Rationale: Molarity is defined as the number of moles of solute per liter of solution. In this case, 5 g of NaCl represents 1 mole of NaCl. Given that this 1 mole is dissolved in 500 L of solution, the molarity of the solution can be calculated as follows: Molarity = moles of solute / liters of solution = 1 mole / 500 L = 0.002 M. However, the molarity is usually expressed in moles per liter, so to convert to M, you divide by 0.085 L (which is 500 L in liters) to get 11.7 M. Choice A is incorrect because the molarity is not 1.0 M. Choice B is incorrect because the molarity is not 2.0 M. Choice D is incorrect because the molarity can be determined from the information provided.

2. What happens during anaphase?

A. Chromosomes move to opposite ends of the spindle.
B. Nuclear membrane and nucleoli disintegrate.
C. Chromatids line up at the center of the spindle.
D. Nuclear membrane and nucleoli form.

Correct answer: A

Rationale: During anaphase, the sister chromatids, joined at the centromere, separate and move towards opposite ends of the spindle apparatus. This movement ensures that each daughter cell receives an identical set of chromosomes. Choice B is incorrect as the disintegration of the nuclear membrane and nucleoli occurs during prophase. Choice C is incorrect as chromatids align at the center of the spindle during metaphase, not anaphase. Choice D is incorrect as the formation of the nuclear membrane and nucleoli occurs during telophase, not anaphase.

3. Children generally ______ with others of the same size and age.

A. Play
B. Plays
C. Played
D. Playing

Correct answer: A

Rationale: The correct answer is 'Play' because 'Children' is a plural subject and requires the base form of the verb. When referring to a plural subject like 'Children,' the verb should be in its base form without an added 's' or 'ed.' In this context, 'Play' is the appropriate form to use to match the subject 'Children.' Choice B, 'Plays,' is incorrect because it is the singular form of the verb and does not agree with the plural subject 'Children.' Choice C, 'Played,' is incorrect as it is the past tense form of the verb and does not fit the present tense context of the sentence. Choice D, 'Playing,' is incorrect as it is the present participle form of the verb and does not match the simple present tense needed in the sentence.

4. What does intact mean?

A. Damaged
B. In place, unharmed
C. Destroyed
D. Incomplete

Correct answer: B

Rationale: The correct answer is B: 'In place, unharmed.' 'Intact' refers to something that is whole, undamaged, or unharmed. Choices A, C, and D are incorrect because they describe states opposite to what intact means. 'Damaged,' 'Destroyed,' and 'Incomplete' all signify a lack of wholeness or harm, which is contrary to the meaning of intact.

5. Select the word or phrase that makes the following sentence grammatically correct: 'Why did we ____ try so hard?'

A. has to
B. haven't
C. had to
D. have to

Correct answer: D

Rationale: 'Have to' is the correct choice as it fits the sentence structure. The sentence is in the past tense ('did we') and requires the infinitive form 'have to' to express the idea of necessity or obligation in the past. 'Has to' (Choice A) is incorrect as it is present tense, 'haven't' (Choice B) is a negative form and does not make sense in this context, and 'had to' (Choice C) would imply a past obligation that has already been fulfilled, which is not the intended meaning here.