Nokea
Rusting of iron is an example of
- A. Endothermic reaction
- B. Exothermic reaction
- C. Single displacement reaction
- D. Photochemical reaction
Correct Answer: A
Rationale: The rusting of iron is an endothermic reaction. This means that it absorbs heat from its surroundings to occur. Rusting involves the slow oxidation of iron in the presence of oxygen and water. As energy is absorbed during this process, it is classified as an endothermic reaction. Choice B, an exothermic reaction, releases heat instead of absorbing it, which is not the case in rusting. Choices C and D are unrelated to the process of rusting and do not involve the absorption of heat from the surroundings.
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Which term in physics describes the resistance of an object to changes in its motion?
- A. Inertia
- B. Momentum
- C. Gravity
- D. Kinetic energy
Correct Answer: A
Rationale: Inertia is the term that describes the resistance of an object to changes in its motion. This property is explained by Newton's First Law of Motion, which states that objects tend to maintain their state of motion unless acted upon by an external force. Inertia is closely related to mass, where objects with more mass exhibit more resistance to changes in motion. Momentum (B) is the product of an object's mass and velocity, gravity (C) is the force of attraction between objects, and kinetic energy (D) is the energy associated with an object's motion. Therefore, the correct answer is A because inertia specifically addresses the resistance of an object to changes in its motion.
In the context of cholesterol levels, LDL cholesterol is often referred to as:
- A. HDL or "good" cholesterol.
- B. LDL or "bad" cholesterol.
- C. Total cholesterol, encompassing both LDL and HDL.
- D. VLDL, a type of triglyceride transported in the bloodstream.
Correct Answer: B
Rationale: LDL cholesterol is often referred to as "bad" cholesterol because high levels of LDL can lead to plaque buildup in the arteries, increasing the risk of heart disease and stroke. LDL cholesterol is considered harmful as it contributes to the formation of plaque in blood vessels, whereas HDL cholesterol helps remove LDL from the arteries. Choice A is incorrect because HDL is known as "good" cholesterol, which helps remove LDL cholesterol from the bloodstream. Choice C is incorrect as it refers to total cholesterol, which includes LDL, HDL, and other lipids. Choice D is incorrect as VLDL is a different type of lipoprotein that carries triglycerides and is not specifically related to LDL cholesterol.
Which property of a substance refers to its ability to be stretched into thin wires?
- A. Conductivity
- B. Viscosity
- C. Ductility
- D. Malleability
Correct Answer: C
Rationale: Ductility is the property of a substance that allows it to be stretched into thin wires without breaking. It is a crucial property for materials used in wire production. Conductivity refers to the ability of a substance to conduct electricity or heat, not to be stretched into wires. Viscosity is the measure of a fluid's resistance to flow, not its ability to be stretched. Malleability is the property of a substance that allows it to be hammered or rolled into thin sheets, not stretched into wires.
Define 'friction' in terms of opposing motion.
- A. A force that increases motion
- B. A force that accelerates motion
- C. A force that opposes motion
- D. A force that creates motion
Correct Answer: C
Rationale: Friction is a force that opposes motion. When two surfaces are in contact, friction acts in the opposite direction to the motion or the potential motion between the two surfaces. It resists the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Friction hinders or prevents motion rather than promoting it. Choices A, B, and D are incorrect as they suggest that friction increases, accelerates, or creates motion, which is inaccurate. The correct definition of friction is that it opposes motion, making choice C the most appropriate option.
What type of nuclear force is responsible for holding protons and neutrons together in the nucleus of an atom?
- A. Electromagnetism
- B. Gravity
- C. Strong nuclear force
- D. Weak nuclear force
Correct Answer: C
Rationale: The correct answer is the strong nuclear force. It is an incredibly powerful force that overcomes the repulsive electrostatic force between protons, binding them together and stabilizing the nucleus. The strong nuclear force is essential for maintaining the integrity and stability of an atom's nucleus. Electromagnetism (Choice A) is responsible for interactions between charged particles but is not the primary force holding the nucleus together. Gravity (Choice B) is a very weak force at the nuclear level and is not responsible for binding protons and neutrons in the nucleus. The weak nuclear force (Choice D) is involved in certain types of radioactive decay processes, but it is not the force responsible for holding the nucleus together.