Q: Relative humidity is defined as:

$$\frac{\text{partial pressure of } H_2O}{\text{saturation pressure of } H_2O} \times 100\%$$

Question 1

Which of the following best describes the internal energy of an ideal monatomic gas?

Accepted Answer

The sum of the kinetic energy of all particles only.

Question 2

A 12.0 kg object descends 1.25 m at constant speed, and this is repeated 20 times. If all the work done by gravity is used to heat water, how much water (in kg) could be raised by 1°C? (Assume $$1 \ 	ext{cal} = 4.186 \ 	ext{J}$$, $$1 \ 	ext{cal}$$ raises $$1 \ 	ext{g} of $$water by $$1^{\circ}$$	ext{C}$$.)

Accepted Answer

$$0.702 \ 	ext{kg}$$

Question 3

Which of the following is NOT included in the internal energy of a system?

Accepted Answer

Kinetic energy due to external forces (e.g., gravity)

Question 4

The specific heat capacity of water is $$4186 \ 	ext{J}/	ext{kg} \cdot 	ext{K}. $$How much heat is required to raise the temperature of $$5.0 \ 	ext{kg} of $$water from $$20^{\circ}$$	ext{C}$$ to 30$$^{\circ}$$	ext{C}$$?

Accepted Answer

$$209,300 \ 	ext{J}$$

Question 5

Which process describes heat transfer through direct molecular collisions in a solid?

Accepted Answer

Conduction

Question 6

A cylinder contains $$250 \ 	ext{L} of $$xenon gas at $$20^{\circ}$$	ext{C}$$ and 5.0$$ \ 	ext{atm}$$. How much heat is required to raise the temperature to 50$$^{\circ}$$	ext{C} at $$constant volume? (Treat Xe as a monatomic ideal gas, $$C_V = \frac{3}{2}R.)$$

Accepted Answer

$$Q = n C_V \Delta T$$

Question 7

Which of the following statements about the critical point on a phase diagram is correct?

Accepted Answer

It is the temperature and pressure above which the liquid and gas phases are indistinguishable.

Question 8

The Maxwell distribution of molecular speeds shows that as temperature increases:

Accepted Answer

The most probable speed increases and the distribution broadens.

Question 9

Which equation correctly relates the average kinetic energy of a molecule to temperature?

Accepted Answer

$$\langle KE \rangle = \frac{1}{2} m v^2$ = \frac{3}{2} k T$$

Question 10

A freezer is insulated with $$5 \ 	ext{cm}$$ thick styrofoam ($$k = 0.035 \ 	ext{J}/	ext{s} \cdot 	ext{m} \cdot 	ext{K}). If $$the inside is $$-20^{\circ}$$	ext{C}$$ and the outside is 25$$^{\circ}$$	ext{C}$$, what is the rate of heat flow through $$7.24 \ 	ext{m}^2 of $$insulation?

Accepted Answer

$$220 \ 	ext{J}/	ext{s}$$

Question 11

Which of the following is the correct definition of specific heat capacity?

Accepted Answer

The amount of heat required to raise the temperature of $$1 \ 	ext{kg} of a $$substance by $$1 \ 	ext{K}.$$

Question 12

If the cost of electricity is $$0.08$$ per kW-hr, what does it cost to heat $$160 \ 	ext{L} of $$water from $$10^{\circ}$$	ext{C}$$ to 70$$^{\circ}$$	ext{C}$$? ($$c = 4186 \ 	ext{J}/	ext{kg} \cdot 	ext{K}$$, $$1 \ 	ext{kW-hr} = 3.6 	imes 10^6$ \ 	ext{J}$$, $$1 \ 	ext{L} = 1 \ 	ext{kg}$$ for water)

Accepted Answer

$$1.49$$

Question 13

Which of the following is NOT a method of heat transfer?

Accepted Answer

Compression

Question 14

Relative humidity is defined as:

Accepted Answer

$$\frac{	ext{partial pressure of } H_2O}{	ext{saturation pressure of } H_2O} 	imes 100\%$$

Question 15

Which of the following best describes the process of sublimation?

Accepted Answer

Solid to gas

Question 16

Which of the following factors does NOT increase the rate of heat conduction through a wall?

Accepted Answer

Increasing the thickness of the wall

Question 17

For an ideal monatomic gas, the internal energy $$U is $$given by:

Accepted Answer

$$U = \frac{3}{2} nRT$$

Question 18

Which of the following is true about the triple point of a substance?

Accepted Answer

It is the unique temperature and pressure where solid, liquid, and gas phases coexist in equilibrium.

Heat and Calorimetry I: Internal Energy, Phase Changes, and Heat Transfer

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