HESI A2
HESI A2 Chemistry Practice Test
1. What is the typical oxidation state of oxygen in most compounds?
- A. -1
- B. -2
- C. 0
- D. -3
Correct answer: B
Rationale: The correct answer is B: "-2". Oxygen usually exhibits an oxidation state of -2 in most compounds. This is due to oxygen's high electronegativity, which causes it to attract electrons, leading to the gain of two electrons in chemical reactions. Choice A (-1) is incorrect because oxygen rarely has an oxidation state of -1 in compounds. Choice C (0) is incorrect as oxygen does not usually have an oxidation state of zero in compounds. Choice D (-3) is incorrect as oxygen does not commonly have an oxidation state of -3 in compounds.
2. Enthalpy (H) is a thermodynamic property defined as the sum of a system's internal energy (U) and the product of its pressure (P) and volume (V). The relationship between these is:
- A. H = U + PV
- B. H = U - PV
- C. H = U / PV
- D. H = PV / U
Correct answer: A
Rationale: Enthalpy (H) is defined as H = U + PV, where U represents internal energy, P is pressure, and V is volume. Enthalpy includes both the internal energy of a system and the energy required to create space for the system against an external pressure. Therefore, the correct relationship between enthalpy, internal energy, pressure, and volume is H = U + PV. Choice B is incorrect as subtracting PV would not account for the work done against pressure. Choice C is incorrect as dividing U by PV doesn't represent the definition of enthalpy. Choice D is incorrect as dividing PV by U is not the correct relationship based on the definition of enthalpy.
3. Train A leaves the station at 1:45 traveling at a constant speed of 65 mph. If it arrives at its destination at 3:15, how many miles did it travel?
- A. 97.5 miles
- B. 75 miles
- C. 100 miles
- D. 130 miles
Correct answer: A
Rationale: Train A traveled for 1.5 hours at a speed of 65 mph. To find the distance traveled, we use the formula Distance = Speed x Time. Distance = 65 mph x 1.5 hours = 97.5 miles. Therefore, the correct answer is 97.5 miles. Choice B (75 miles) is incorrect because it does not account for the full 1.5 hours of travel time. Choice C (100 miles) and Choice D (130 miles) are incorrect as they are not calculated based on the given speed and time.
4. How many milliliters are in 1 liter?
- A. 100 mL
- B. 1,000 mL
- C. 500 mL
- D. 50 mL
Correct answer: B
Rationale: There are 1,000 milliliters in 1 liter. The prefix 'milli-' means one-thousandth, so when converting from liters to milliliters, you multiply by 1,000. Therefore, the correct answer is 1,000 mL. Choice A (100 mL) is incorrect as it represents one-tenth of the correct conversion. Choice C (500 mL) is incorrect as it is half of the correct conversion. Choice D (50 mL) is incorrect as it is one-twentieth of the correct conversion.
5. A table shows the average blood pressure readings for different age groups. How do you determine the highest average systolic pressure?
- A. Find the largest number in the "systolic pressure" column.
- B. Compare the means (averages) of each age group.
- C. Add all systolic pressure values and divide by the total number of patients.
- D. Subtract the lowest systolic pressure from the highest.
Correct answer: A
Rationale: Rationale: - To determine the highest average systolic pressure, you need to identify the highest individual systolic pressure reading in the dataset. - Option A instructs you to find the largest number in the "systolic pressure" column, which directly addresses the task of identifying the highest systolic pressure reading. - Comparing means (Option B) would not necessarily give you the highest individual systolic pressure reading, as averages can be influenced by the distribution of values within each age group. - Adding all systolic pressure values and dividing by the total number of patients (Option C) would give you the overall average systolic pressure, not the highest individual reading. - Subtracting the lowest systolic pressure from the highest (Option D) would give you the range of systolic pressures, not specifically the highest individual reading. Therefore, the correct approach to determine the highest average systolic pressure
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