HESI Exams Quizlet Physics

Correct Answer: D

Rationale: The correct answer is D: Dry ice. Dry ice is solid carbon dioxide that sublimes directly into carbon dioxide gas without melting into a liquid state. This process can be observed in everyday situations, such as when dry ice "evaporates" in a cooler. Iron (A) and Silver (B) do not undergo sublimation but instead melt into liquid phases. Salt crystal (C) also melts into a liquid (brine solution) before evaporating.

Correct Answer: A

Rationale: Semiconductors fall between conductors and insulators in terms of electrical conductivity because they have conductivity levels higher than insulators but lower than conductors. Conductors have high conductivity due to abundant free electrons, while insulators have very low conductivity due to the lack of free electrons. Semiconductors can conduct electricity under certain conditions by manipulating the number of free electrons through doping or applying electric fields. Therefore, choice A is correct. Choices B, C, and D are incorrect because they do not accurately represent the conductivity levels of semiconductors in relation to other materials.

Correct Answer: A

Rationale: To find the current flowing through the flashlight, use Ohm's Law: Current (I) = Voltage (V) / Resistance (R). Given V=3V and R=60Ω, I = 3V / 60Ω = 0.05 amp (A). This is the correct answer. Choice B, 0.5 amp, is incorrect as it does not match the calculated value. Choice C and D, 1.8 amp and 18 amp respectively, are also incorrect as they are significantly higher than the calculated current value and would require a much higher voltage source.

Correct Answer: A

Rationale: The correct answer is A: 10 m/s. Velocity is calculated by dividing the distance traveled by the time taken. In this case, velocity = 100m / 10s = 10 m/s. Choice B, 90 m/s, is incorrect because it is not the accurate calculation. Choice C, 110 m/s, and choice D, 1,000 m/s, are both incorrect as they do not align with the correct formula for calculating velocity. The key is to remember that velocity is a vector quantity that includes both speed and direction, and in this case, we are only concerned with the speed of the object, making choice A the correct answer.

Correct Answer: B

Rationale: In an isobaric process (constant pressure), work done is given by W = PΔV. Since the pressure is constant, work done is directly proportional to the volume change. As volume increases, work is done by the system, making it positive. If volume decreases, work is done on the system, making it negative. Choice A is incorrect as work is done even if volume change is zero. Choice C is incorrect as work's sign depends on the direction of volume change. Choice D is incorrect as work done is indeed dependent on pressure and volume change in an isobaric process.