1.
Solid X is placed in contact with solid Y. Heat energy will flow spontaneously from X to Y when
Correct Answer
B. X is 10°C and Y is 5°C
Explanation
When two objects are in contact, heat energy will flow spontaneously from the object with higher temperature to the object with lower temperature until both objects reach thermal equilibrium. In this case, X is at a higher temperature (10°C) compared to Y (5°C), so heat energy will flow from X to Y.
2.
As water warms from 50°C to 85°C, the kinetic energy of the molecules will
Correct Answer
A. Increase
Explanation
As water warms from 50°C to 85°C, the kinetic energy of the molecules will increase. This is because as the temperature of a substance increases, the average kinetic energy of its molecules also increases. The increase in temperature causes the molecules to move faster and collide more frequently, resulting in an increase in their kinetic energy. Therefore, the correct answer is increase.
3.
The temperature of a sample of pudding is a measure of the ___________ of the particles that make up the pudding.
Correct Answer
B. Kinetic energy
Explanation
The temperature of a sample of pudding is a measure of the kinetic energy of the particles that make up the pudding. Temperature is a measure of the average kinetic energy of the particles in a substance. As the particles in the pudding gain energy, they move faster and their kinetic energy increases, resulting in an increase in temperature. Therefore, the correct answer is kinetic energy.
4.
Boiling spaghetti noodles is an example of
Correct Answer
B. Convection
Explanation
Boiling spaghetti noodles is an example of convection because it involves the transfer of heat through the movement of particles in a fluid. When the water is heated, the hotter water rises to the top while the cooler water sinks to the bottom. This creates a circular motion, known as convection currents, which evenly distributes the heat and cooks the spaghetti noodles. Convection is the most appropriate answer because it specifically refers to the transfer of heat through the movement of fluids.
5.
Using a solar cooker is an example of
Correct Answer
C. Radiation
Explanation
Using a solar cooker involves the transfer of heat through radiation. In this process, heat energy is transferred from the sun to the cooker without the need for any physical contact or movement of particles. The solar cooker absorbs the sun's radiation and converts it into heat, which is then used for cooking food. This method eliminates the need for conduction or convection, as the heat is directly received from the sun through electromagnetic waves. Combustion, on the other hand, involves the burning of fuel and is not applicable in the context of using a solar cooker.
6.
An egg frying in a skillet is an example of
Correct Answer
A. Conduction
Explanation
When an egg fries in a skillet, heat is transferred from the hot skillet to the egg through direct contact. This process is known as conduction. Conduction occurs when heat energy is transferred between objects or substances that are in direct contact with each other. In this case, the skillet transfers its heat energy to the egg, causing it to cook and fry.
7.
Products of a complete combustion are
Correct Answer
B. Water and carbon dioxide.
Explanation
During complete combustion, a fuel reacts with oxygen to produce heat, water, and carbon dioxide. This process occurs when there is an adequate supply of oxygen, allowing for the complete oxidation of the fuel. In this case, the correct answer is "water and carbon dioxide" because these are the main products of complete combustion. Oxygen is not produced as it is the reactant, and hydrogen is not mentioned as a product in the options provided.
8.
As matter changes from solid to a liquid energy is
Correct Answer
A. Absorbed
Explanation
When matter changes from a solid to a liquid, energy is absorbed. This is because the process of melting requires the input of energy to break the intermolecular forces holding the particles in a solid together. As the solid absorbs energy, its particles gain enough energy to overcome these forces and transition into a liquid state. Therefore, the correct answer is "absorbed."
9.
What are 2 requirements for a combustion reaction to occur?
Correct Answer
A. Fuel & oxygen
Explanation
A combustion reaction requires two main components: fuel and oxygen. Fuel provides the necessary energy source, such as a hydrocarbon, while oxygen acts as the oxidizing agent. When fuel and oxygen combine in the presence of heat or a spark, a combustion reaction occurs, resulting in the release of energy in the form of heat and light. The other options, carbon dioxide and oxygen, as well as water and oxygen, are the products of a combustion reaction rather than the requirements for it to occur.
10.
Heat is defined as
Correct Answer
A. The amount of kinetic energy.
Explanation
Heat is defined as the amount of kinetic energy. Heat is the energy transferred between two objects or systems due to a temperature difference. Kinetic energy refers to the energy of motion, and in the context of heat, it represents the random motion of particles within a substance. As the temperature of a substance increases, the kinetic energy of its particles also increases, resulting in the transfer of heat energy. Therefore, heat is directly related to the amount of kinetic energy present in a substance.
11.
Ice can heat an object
Correct Answer
C. If the object is colder than the ice.
Explanation
When an object is colder than ice, heat transfer occurs from the object to the ice. Ice has a lower temperature than the object, so heat flows from the warmer object to the colder ice, causing the ice to heat up and melt. Therefore, ice can heat an object if the object is colder than the ice.
12.
Heat transfers from ________ to ________
Correct Answer
A. Hot, cold
Explanation
Heat transfers from hot objects to cold objects due to the difference in temperature. This is because heat naturally flows from areas of higher temperature to areas of lower temperature in an attempt to achieve thermal equilibrium. Therefore, the correct answer is "hot, cold" as heat will transfer from the hotter object to the colder object.
13.
If I stick a metal skewer (stick) into a potato, the amount of cooking time required will
Correct Answer
A. Decrease
Explanation
When a metal skewer is inserted into a potato, it acts as a conductor of heat, allowing the heat to transfer more efficiently to the center of the potato. This reduces the cooking time required as the heat is distributed more evenly throughout the potato. Therefore, the cooking time will decrease.
14.
If object X has a temperature of 90° C and object Y has a temperature of 20°C, when they are placed in contact with each other the final temperature of each will be approximately
Correct Answer
C. 55°C
Explanation
When two objects with different temperatures are placed in contact with each other, heat will flow from the object with higher temperature to the object with lower temperature until they reach thermal equilibrium. In this case, object X with a temperature of 90°C will transfer heat to object Y with a temperature of 20°C. As a result, the final temperature of each object will be somewhere in between the initial temperatures. The approximate final temperature will be the average of the initial temperatures, which is (90°C + 20°C) / 2 = 55°C.
15.
As matter changes from a liquid to a solid entropy
Correct Answer
B. Decreases
Explanation
When matter changes from a liquid to a solid, the particles in the substance become more ordered and arranged in a fixed pattern. This decrease in randomness and disorder leads to a decrease in entropy. Entropy is a measure of the randomness or disorder of a system, so as the liquid becomes a solid, the level of disorder decreases, causing a decrease in entropy.
16.
When a liquid evaporates what cools?
Correct Answer
C. The surroundings
Explanation
When a liquid evaporates, the process requires energy from its surroundings. This energy is used to break the intermolecular forces holding the liquid molecules together and convert them into gas molecules. As a result, the surroundings lose energy, causing a cooling effect. Therefore, the correct answer is that the surroundings cool when a liquid evaporates.
17.
A campfire eventually burns out because
Correct Answer
A. You stop giving it fuel (wood, paper, lighter fluid, etc)
Explanation
The correct answer is that the campfire eventually burns out because you stop giving it fuel. This is because fire requires fuel to sustain itself. Without a continuous supply of wood, paper, lighter fluid, or any other combustible material, the fire will gradually consume all available fuel and eventually die out.
18.
As the amount of cooking time increases, the amount of heat transfer
Correct Answer
B. Increases
Explanation
As the amount of cooking time increases, the amount of heat transfer increases. This is because the longer the food is cooked, the more time it has to absorb heat from the cooking source. Therefore, there is a greater transfer of heat from the source to the food, resulting in an increase in the amount of heat transfer.
19.
Matter melting _________________ energy.
Correct Answer
A. Absorbs
Explanation
When matter undergoes melting, it absorbs energy. This is because the process of melting requires the input of heat energy to break the bonds between the particles and convert the solid into a liquid. As the energy is absorbed, the particles gain enough energy to overcome the forces holding them together in a solid state, resulting in the phase transition from solid to liquid. Therefore, the correct answer is "absorbs".
20.
Matter condensing is an _______________ process.
Correct Answer
B. Releases
Explanation
When matter condenses, it goes from a gaseous or vapor state to a more condensed state, such as a liquid or solid. This process involves the release of energy in the form of heat. As the particles of matter come closer together and slow down, they release energy, which is why condensation is a releasing process.