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When two objects with different masses collide, what happens to their momentum after the collision?
- A. Increases for both objects
- B. Decreases for both objects
- C. Remains the same for both objects
- D. Can increase for one and decrease for the other
Correct Answer: C
Rationale: When two objects with different masses collide, their total momentum remains the same after the collision according to the law of conservation of momentum if no external forces are acting on them. This means that the momentum of each individual object may change, but the sum of their momenta will remain constant. Choice A is incorrect because the total momentum of the system is conserved. Choice B is incorrect because momentum is conserved in an isolated system. Choice D is incorrect as it implies a violation of the law of conservation of momentum, which states that the total momentum of an isolated system remains constant.
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What do isotopes of the same element have in common?
- A. Identical number of protons and neutrons.
- B. Identical chemical properties.
- C. Identical number of electrons.
- D. Identical mass number.
Correct Answer: D
Rationale: Isotopes of the same element have the same number of protons, which defines the element, but different numbers of neutrons. This difference in neutron count results in isotopes of the same element having different mass numbers. Chemical properties are determined by the arrangement of electrons in an atom, so isotopes of the same element may exhibit slightly different chemical behaviors due to different neutron numbers. The number of electrons can vary in isotopes, affecting their charge. However, the mass number, which is the sum of protons and neutrons, is the same for isotopes of the same element. Therefore, the correct answer is that isotopes of the same element share an identical mass number.
In physics, what does the term 'net force' refer to?
- A. Total force acting on an object
- B. Force due to gravity
- C. Force in motion
- D. Force of friction
Correct Answer: A
Rationale: In physics, the term 'net force' refers to the total force acting on an object, considering all individual forces acting on it. It is crucial in determining the object's motion and acceleration as it represents the overall force applied to the object. Choice B, 'Force due to gravity,' is incorrect as it refers to a specific force acting on an object due to gravity. Choice C, 'Force in motion,' is incorrect as it does not define the concept of net force. Choice D, 'Force of friction,' is incorrect as it specifically refers to the force opposing motion when two surfaces are in contact.
When sugar is heated, it breaks down into carbon and water vapor. This is an example of a:
- A. Combination reaction
- B. Decomposition reaction
- C. Double displacement reaction
- D. Single displacement reaction
Correct Answer: B
Rationale: The correct answer is B: Decomposition reaction. When sugar is heated, it undergoes a decomposition reaction where it breaks down into simpler substances, carbon, and water vapor. In a decomposition reaction, a single compound breaks down into two or more simpler substances. This process is the opposite of a combination reaction where two or more substances combine to form a new compound. Choice A, Combination reaction, is incorrect because a combination reaction involves the combination of two or more substances to form a new compound, which is the opposite of what happens when sugar breaks down. Choices C and D, Double displacement reaction and Single displacement reaction, are incorrect as they involve different mechanisms where the atoms or ions of the reactants are exchanged, which is not the case in the breakdown of sugar into carbon and water vapor.
What is the process of converting DNA into a protein called?
- A. Transcription
- B. Translation
- C. Replication
- D. Mutation
Correct Answer: B
Rationale: Translation is the correct answer. It is the process of converting the information in mRNA into a sequence of amino acids to form a protein. Transcription (Choice A) is the process of copying a segment of DNA into RNA. Replication (Choice C) is the process of making an identical copy of DNA. Mutation (Choice D) refers to a change in the DNA sequence that can lead to variations in proteins, but it is not the process of converting DNA into a protein.
Which of the following statements about prions is TRUE?
- A. They are composed of proteins only
- B. They are easily destroyed by common disinfectants
- C. hey are a type of antibiotic
- D. They are a live organism
Correct Answer: A
Rationale: A) This statement is true. Prions are infectious agents composed entirely of protein, lacking nucleic acids such as DNA or RNA. They are known for causing neurodegenerative diseases in animals and humans.
B) This statement is false. Prions are not easily destroyed by common disinfectants due to their unique structure and resistance to conventional sterilization methods.
C) This statement is false. Prions are not a type of antibiotic. They are a distinct class of infectious agents.
D) This statement is false. Prions are not live organisms but rather misfolded proteins that can induce abnormal folding in normal proteins, leading to disease.