Explanation:

60$J$ per second gives power, P=60W

$A$ therefore the answer is A.

I. Incorrect: As the heater heats both the water and the container, the container itself gains energy to increase temperature. Greater specific heat capacity means more energy is required to result in the same temperature change. So, for the glass container less energy is needed to reach 100oC which will take less time.

II. Correct: When there is isolation for the container there is less heat lost to the surroundings, resulting in higher efficiency. So the boiling finishes earlier.

III. Correct: As the amount of water increases more energy is required to result in same temperature change.

The change of state will occur at the same temperature as the original graph but take less time to complete.

Explanation:
Gas pressure is caused by the particles colliding with the walls, applying a force to them. It is related to the rate of particle-wall collisions per unit surface area of the container per unit time.

A is incorrect because with an increased number of particles more particle-wall collisions will occur and that will lead to a greater rate of collision per unit surface area of cylinder per unit time since there will be no change in the speed of the particles.

B is incorrect because actually the additional particles bring in more kinetic energy so the existing kinetic energy is not being distributed over a larger number of particles. Additionally, since the temperature is being kept constant, the average kinetic energy is constant.

C is correct because there are now more particles in the same volume, the rate of collision per unit surface area of the cylinder per unit time will increase.

D is incorrect because there is no change in the average speed of the particles due to the temperature remaining the same. Temperature is related to the average kinetic energy of the particles, and the particle kinetic energy depends on the speed of the particles.

Explanation:
To calculate $n$, the student would rearrange the formula to get

• n=PV/RT

In both operations, the percentage uncertainty must be added, therefore the correct answer is C (2 % + 6 % + 1 % = 9 %)

Explanation:

Once the switch is closed, the heating element in the circuit on the left  increases in temperature.

This increase affects the thermistor by decreasing its resistance. As a result the current in the circuit on the right increases, causing the lamp's brightness to increase.

Explanation:

Uranium-235 is a rare radioactive isotope on Earth, extracted from uranium ores. The available uranium is limited and will be depleted in time. Biomass will replenish in a human lifetime, so is considered renewable.

Explanation:
E=mcΔTE=Pt

Pt=mcΔT

ΔT=Pt/mc

Doubling energy transfer rate will double the temperature rise. Halving the mass will also double the temperature rise. The change in temperature will be 4 times larger than the initial case, which is 40oC. This

gives the final temperature as 60oC.

Explanation:
373$K$ is the boiling point of water. Temperature does not change until all water is boiled. B and C show temperature change at $t=0$. D is not compatible with the question. You might have seen graphs that resemble options B and D in this context, they are there to distract you.

Explanation:

The energy $E$ required to completely melt each substance is given by

• E=mL

where $m$ is the mass of the substance and $L$ is the specific latent heat of fusion.

Therefore, for a given power $P$, the duration tmelt of the plateau obeys the equation

tmelt=mL/P

The two substances have equal values of $m$ and $P$, meaning that since Substance $A$ has a higher tmelt value than Substance $B$, it also possesses a higher $L$ value. Hence, Statement III is incorrect.

The rates of temperature change before and after melting are related to the specific heat capacity $c$ via the expression

• E = mcΔT
• PΔt=mcΔT
• ΔTΔt=Pmc

The gradient of the graph is therefore inversely proportional to $c$.

In both solid and liquid state, Substance $A$ exhibits a higher value of ΔTΔt than Substance $B$, meaning that has a lower value of $c$. Hence, Statement I is correct.

Furthermore, for each substance, the gradient of the graph is lower in the liquid phase than in the solid phase, which means that after melting $c$ increases and Statement II is correct.

Explanation:
Statement I is correct. The scattering of sunlight returns part of the sunlight back to space, reducing intensity on the ground.

Statement II is correct. The rotation of earth causes day and night, reducing the time the solar panel is exposed to sunlight and also changing the incident angle of sunlight on the panel.

Statement III is correct. The intensity on the solar panel is maximum when its surface is perpendicular to incident sunlight, but due to the seasons, the time of day and the installation angle of the panel the sunlight will not be normally incident on the panel.

Thus, D is the answer.

Explanation:

The net change in the internal energy of a cyclic process is zero because it returns to its original temperature after each cycle. This means that statement I is correct.

The total change in entropy is zero for any reversible cycle. This means that statement II is correct as the gas returns to its original state each cycle.

The graph is for a heat engine, which takes in heat and does work on the environment. Therefore statement III is incorrect. A clockwise cycle always does net positive work on the environment.

Explanation:
Temperature appears to be doubled; but that is using the celsius scale. Absolute temperature is not doubled. So, $D$ is incorrect.

Volume cannot change, since the container's volume is fixed. The number of moles cannot change since the gas is enclosed in the container.

Hence, pressure is proportional to absolute temperature:

p2/p=[273+542]/[73+27] ⇒p2=1.09p

Explanation:
Due to the fixed volume, the separation between the gas molecules decreases. According to the ideal gas law, the pressure of the gas will increase and so does the collision frequency. The mass of the container will also be greater with the addition of more gas in the container. The only constant quantity is the average size of the molecules. It is dependent on molecular structure only. Therefore the answer is C.