Heat & Temperature
Q. A 500 g block of ice at -10°C is heated until it melts completely and the water is at 0°C. How much heat is required? (Specific heat of ice = 2.1 J/g°C, Latent heat of fusion = 334 J/g) (2000)
A.
1050 J
B.
1340 J
C.
1500 J
D.
2000 J
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Solution
Heat to raise ice to 0°C = 500g * 2.1 J/g°C * 10°C = 10500 J. Heat to melt = 500g * 334 J/g = 167000 J. Total = 1050 J + 167000 J = 1340 J.
Correct Answer: B — 1340 J
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Q. A metal block of mass 2 kg at 100°C is placed in 1 kg of water at 20°C. What is the final temperature of the system? (Specific heat of water = 4.2 J/g°C, Specific heat of metal = 0.9 J/g°C)
A.
30°C
B.
40°C
C.
50°C
D.
60°C
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Solution
Using conservation of energy: m1*c1*(T1-Tf) = m2*c2*(Tf-T2). Solving gives Tf = 50°C.
Correct Answer: C — 50°C
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Q. How much heat is required to convert 1 kg of water at 100°C to steam at 100°C? (Latent heat of vaporization = 2260 J/g)
A.
1000 J
B.
2260 J
C.
2260000 J
D.
100000 J
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Solution
Q = m * L = 1000 g * 2260 J/g = 2260000 J.
Correct Answer: C — 2260000 J
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Q. If 1 kg of water is heated from 20°C to 100°C, how much heat is absorbed? (Specific heat of water = 4.2 J/g°C)
A.
3360 J
B.
4000 J
C.
4200 J
D.
4800 J
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Solution
Q = m*c*ΔT = 1000 g * 4.2 J/g°C * (100°C - 20°C) = 4200 J.
Correct Answer: C — 4200 J
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Q. If 100 g of water at 0°C is mixed with 100 g of water at 100°C, what will be the final temperature?
A.
50°C
B.
25°C
C.
75°C
D.
0°C
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Solution
The final temperature will be 50°C due to equal masses and specific heat capacities.
Correct Answer: A — 50°C
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Q. If 100 g of water at 0°C is mixed with 100 g of water at 100°C, what will be the final temperature of the mixture?
A.
50°C
B.
25°C
C.
75°C
D.
0°C
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Solution
Using the principle of conservation of energy, the final temperature will be 50°C.
Correct Answer: A — 50°C
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Q. If 100 g of water at 80°C is mixed with 200 g of water at 20°C, what will be the final temperature?
A.
30°C
B.
40°C
C.
50°C
D.
60°C
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Solution
Using the principle of conservation of energy, the final temperature can be calculated to be 40°C.
Correct Answer: B — 40°C
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Q. If 200 g of ice at 0°C is added to 100 g of water at 80°C, what will be the final temperature of the mixture? (Latent heat of fusion of ice = 334 J/g)
A.
0°C
B.
20°C
C.
40°C
D.
60°C
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Solution
Heat lost by water = Heat gained by ice. 100g * 80°C = 200g * 334 J/g + 200g * (Tf - 0°C). Solving gives Tf = 20°C.
Correct Answer: B — 20°C
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Q. If 300 g of water at 25°C is mixed with 200 g of water at 75°C, what is the final temperature? (Specific heat of water = 4.2 J/g°C)
A.
40°C
B.
50°C
C.
60°C
D.
70°C
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Solution
Using m1*T1 + m2*T2 = (m1 + m2)*Tf, we find Tf = (300*25 + 200*75) / (300 + 200) = 50°C.
Correct Answer: B — 50°C
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Q. If the temperature of an ideal gas is doubled at constant volume, what happens to its pressure?
A.
It halves
B.
It remains the same
C.
It doubles
D.
It quadruples
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Solution
According to Gay-Lussac's law, pressure is directly proportional to temperature at constant volume, so it doubles.
Correct Answer: C — It doubles
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Q. In which of the following materials does heat transfer occur primarily through conduction?
A.
Metal
B.
Water
C.
Air
D.
Vacuum
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Solution
Heat transfer through conduction occurs primarily in solids, especially metals.
Correct Answer: A — Metal
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Q. In which of the following processes does the internal energy of a system remain constant?
A.
Isothermal process
B.
Adiabatic process
C.
Isobaric process
D.
Isochoric process
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Solution
In an isothermal process, the internal energy of an ideal gas remains constant.
Correct Answer: A — Isothermal process
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Q. In which of the following processes does the temperature of a gas increase?
A.
Isothermal expansion
B.
Adiabatic compression
C.
Isobaric expansion
D.
Isochoric cooling
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Solution
In adiabatic compression, the temperature of a gas increases due to work done on it.
Correct Answer: B — Adiabatic compression
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Q. In which of the following processes does the temperature of a substance remain constant?
A.
Heating
B.
Cooling
C.
Phase change
D.
Compression
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Solution
During a phase change, the temperature of a substance remains constant despite heat being added or removed.
Correct Answer: C — Phase change
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Q. In which of the following processes does the temperature of the system remain constant?
A.
Isothermal process
B.
Adiabatic process
C.
Isobaric process
D.
Isochoric process
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Solution
In an isothermal process, the temperature of the system remains constant.
Correct Answer: A — Isothermal process
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Q. In which of the following scenarios does conduction occur?
A.
Heating water in a pot
B.
Sun warming the Earth
C.
Wind blowing
D.
Ice melting in a drink
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Solution
Conduction occurs when heat is transferred through direct contact, such as heating water in a pot.
Correct Answer: A — Heating water in a pot
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Q. In which process does a gas do work on its surroundings?
A.
Isothermal expansion
B.
Adiabatic compression
C.
Isochoric process
D.
Isobaric process
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Solution
In isothermal expansion, a gas does work on its surroundings as it expands.
Correct Answer: A — Isothermal expansion
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Q. What happens to the temperature of a gas when it expands adiabatically?
A.
It increases
B.
It decreases
C.
It remains constant
D.
It depends on the gas
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Solution
During adiabatic expansion, a gas does work on its surroundings, which results in a decrease in temperature.
Correct Answer: B — It decreases
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Q. What happens to the temperature of a substance during a phase change?
A.
It increases
B.
It decreases
C.
It remains constant
D.
It fluctuates
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Solution
During a phase change, the temperature of a substance remains constant while heat is added or removed.
Correct Answer: C — It remains constant
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Q. What is the effect of increasing the temperature of a gas at constant volume?
A.
Pressure decreases
B.
Pressure increases
C.
Volume increases
D.
Density increases
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Solution
Increasing the temperature of a gas at constant volume results in an increase in pressure, according to Gay-Lussac's law.
Correct Answer: B — Pressure increases
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Q. What is the final temperature when 200 g of water at 90°C is mixed with 300 g of water at 30°C?
A.
50°C
B.
60°C
C.
70°C
D.
80°C
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Solution
Using the formula m1*T1 + m2*T2 = (m1 + m2)*Tf, we find Tf = (200*90 + 300*30) / (200 + 300) = 70°C.
Correct Answer: C — 70°C
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Q. What is the heat required to raise the temperature of 250 g of aluminum from 25°C to 75°C? (Specific heat of aluminum = 0.9 J/g°C)
A.
4500 J
B.
5000 J
C.
6000 J
D.
7000 J
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Solution
Q = m*c*ΔT = 250 g * 0.9 J/g°C * (75°C - 25°C) = 4500 J.
Correct Answer: A — 4500 J
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Q. What is the latent heat of fusion for ice?
A.
334 J/g
B.
2260 J/g
C.
4190 J/g
D.
1000 J/g
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Solution
The latent heat of fusion for ice is approximately 334 J/g.
Correct Answer: A — 334 J/g
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Q. What is the latent heat of fusion?
A.
Heat required to change a solid to a liquid
B.
Heat required to change a liquid to a gas
C.
Heat required to change a gas to a solid
D.
Heat required to change a liquid to a solid
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Solution
Latent heat of fusion is the heat required to change a solid into a liquid at its melting point.
Correct Answer: A — Heat required to change a solid to a liquid
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Q. What is the principle behind a thermometer?
A.
Expansion of liquid with temperature
B.
Contraction of gas with temperature
C.
Change in color with temperature
D.
Change in pressure with temperature
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Solution
Thermometers work on the principle of expansion of liquid (like mercury) with temperature.
Correct Answer: A — Expansion of liquid with temperature
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Q. What is the relationship between temperature and kinetic energy of particles in a substance?
A.
Directly proportional
B.
Inversely proportional
C.
No relationship
D.
Depends on the substance
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Solution
The average kinetic energy of particles in a substance is directly proportional to its temperature.
Correct Answer: A — Directly proportional
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Q. What is the relationship between temperature and kinetic energy of particles?
A.
Directly proportional
B.
Inversely proportional
C.
No relation
D.
Exponential relation
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Solution
The temperature of a substance is directly proportional to the average kinetic energy of its particles.
Correct Answer: A — Directly proportional
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Q. What is the SI unit of temperature?
A.
Celsius
B.
Fahrenheit
C.
Kelvin
D.
Rankine
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Solution
The SI unit of temperature is Kelvin.
Correct Answer: C — Kelvin
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Q. What is the specific heat capacity of water if 500 J of heat is required to raise the temperature of 100 g of water by 5°C?
A.
1 J/g°C
B.
2 J/g°C
C.
4 J/g°C
D.
5 J/g°C
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Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (100 g * 5°C) = 1 J/g°C.
Correct Answer: A — 1 J/g°C
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Q. What is the specific heat capacity of water?
A.
1 J/g°C
B.
4.18 J/g°C
C.
2 J/g°C
D.
0.5 J/g°C
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Solution
The specific heat capacity of water is approximately 4.18 J/g°C.
Correct Answer: B — 4.18 J/g°C
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