Thermal Multiple Choice

The graph shows the variation of pressure p with temperature θ for a fixed mass of an ideal gas at constant volume. What is the gradient of the graph?

• 0.341

• 0.395

• 2.93

• 5.00

Two flasks X and Y are filled with an ideal gas and are connected by a tube of negligible volume compared to that of the flasks. The volume of X is twice the volume of Y .X is held at a temperature of 150 K and Y is held at a temperature of 300 K What is the ratio M_X/M_Y ?

• 0.125

• 0.25

• 4

• 8

The average mass of an air molecule is 4.8 × 10^–26 kgWhat is the mean square speed of an air molecule at 750 K?

• 3.3 × 10⁵ m² s^–2

• 4.3 × 10⁵ m² s^–2

• 6.5 × 10⁵ m² s^–2

• 8.7 × 10⁵ m² s^–2

A transparent illuminated box contains small smoke particles and air. The smoke particles are observed to move randomly when viewed through a microscope. What is the cause of this observation of Brownian motion?

• Smoke particles gaining kinetic energy by the absorption of light.

• Collisions between smoke particles and air molecules.

• Smoke particles moving in convection currents caused by the air being heated by the light.

• The smoke particles moving randomly due to their temperature.

The diagram shows a gas particle about to collide elastically with a wall. Which diagram shows the correct change in momentum Δmv that occurs during the collision?

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A continuous stream of water falls through a vertical distance of 100 m. Assume no thermal energy is transferred to the surroundings. The specific heat capacity of water is 4200 J kg–1 K–1. What is the temperature difference of the water between the top and bottom of the waterfall?

• 0.023 K

• 0.23 K

• 2.3 K

• 4.3 K

A student measures the power of a microwave oven. He places 200 g of water at 23 °C into the microwave and heats it on full power for 1 minute. When he removes it, the temperature of the water is 79 °C .The specific heat capacity of water is 4200 J kg^–1 K^–1. What is the average rate at which thermal energy is gained by the water?

• 780 W

• 840 W

• 1.1 kW

• 4.6 kW

The composition of a carbon dioxide (CO₂) molecule is one atom of C-12 and two atoms of C-14.What is the number of molecules of CO₂ in 2.2 kg of the gas?

• 1.0 × 10²²

• 3.0 × 10²²

• 3.0 × 10²⁵

• 4.7 × 10²⁵

What is the total internal energy of 2.4 mol of an ideal gas which has a temperature of 15 °C?

• 6.0 × 10^–21 J

• 1.4 × 10^–20 J

• 4.5 × 10² J

• 8.6 × 10³ J

An ice cube of mass 0.010 kg at a temperature of 0 °C is dropped into a cup containing 0.10 kg of water at a temperature of 15 °C. What is the maximum estimated change in temperature of the contents of the cup?.

specific heat capacity of water = 4200 J kg⁻¹ K⁻¹.

specific latent heat of fusion of ice = 3.4 × 10⁵ J kg⁻¹

• 1.5 K

• 8.7 K

• 13.5 K

• 15.0 K