a substance with a ph of 3 is how many times more acidic than a substance with a ph of 5
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HESI A2

Chemistry HESI A2 Practice Test

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

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.

2. What is 28% of 100?

Correct answer: A

Rationale: The correct answer is A: 28. To find 28% of 100, you multiply 0.28 (the decimal equivalent of 28%) by 100. This calculation results in 28. Therefore, 28% of 100 is 28. Choice B, 20, is incorrect as it represents 20% of 100. Choice C, 25, is incorrect as it represents 25% of 100. Choice D, 30, is incorrect as it represents 30% of 100.

3. Which part of the brain monitors and controls the body's movement?

Correct answer: C

Rationale: The correct answer is the front portion of the parietal lobe. The motor cortex, located in this area, is responsible for planning, controlling, and executing voluntary movements. It plays a crucial role in coordinating the body's movement. Choice A, the top, middle portion of the parietal lobe, is incorrect as this region is more involved in processing sensory information rather than controlling movement. Choice B, the back of the head, is incorrect as it typically refers to the occipital lobe responsible for processing visual information. Choice D, around the auditory cortex, is incorrect as the auditory cortex is primarily involved in processing auditory information, not controlling body movement.

4. Which of these objects has the greatest momentum?

Correct answer: A

Rationale: Momentum is the product of mass and velocity. The car has the highest momentum because it has the largest mass and a significant velocity.

5. She was so mad at her boyfriend, she _____ on him when he called.

Correct answer: A

Rationale: The correct answer is 'A: hung up.' In this context, 'hung up' is the correct phrasal verb to indicate ending a phone call abruptly. The phrase 'hung up' means to abruptly end a phone call. The other choices do not fit the context. 'Picked' implies selecting something, 'held' means to grasp or support something, and 'held on' implies maintaining a grip or connection rather than ending the call.

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