Nokea
Which of the following is an example of a polymer?
- A. Methane
- B. Ethanol
- C. Polyethylene
- D. Acetic acid
Correct Answer: C
Rationale: The correct answer is C, Polyethylene. Polyethylene is a polymer composed of a large number of repeating ethylene units linked together, forming a long-chain molecule, characteristic of polymers. Methane, ethanol, and acetic acid are small organic molecules that do not demonstrate the repeating unit structure typical of polymers. Therefore, they are not examples of polymers.
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What is the term for the mixture of reactants and products present during a chemical reaction?
- A. Solution
- B. Mixture
- C. Reaction mixture
- D. Precipitate
Correct Answer: C
Rationale: The term 'reaction mixture' is used to describe the combination of both reactants and products that exist simultaneously during a chemical reaction. It encompasses not only the initial substances (reactants) but also the resulting compounds (products) formed throughout the reaction process. Choice A, 'Solution,' typically refers to a homogenous mixture where one substance is dissolved in another. Choice B, 'Mixture,' is a general term that does not specifically indicate the mix of reactants and products in a chemical reaction. Choice D, 'Precipitate,' specifically refers to the solid formed when two solutions react and a solid compound is produced.
Which element shares the same group (family) on the periodic table with helium (He)?
- A. Neon (Ne)
- B. Boron (B)
- C. Carbon (C)
- D. Oxygen (O)
Correct Answer: A
Rationale: Neon (Ne) shares the same group (family) on the periodic table with helium (He). Both helium and neon belong to Group 18 (Noble Gases) due to their complete and stable outer electron shells, making them chemically inert. Boron (B), Carbon (C), and Oxygen (O) are not in the same group as helium. Boron is in Group 13, Carbon is in Group 14, and Oxygen is in Group 16 on the periodic table.
Which type of muscle is found in the walls of hollow organs, such as the stomach and intestines, and is responsible for involuntary contractions to propel substances through the organs?
- A. Cardiac muscle
- B. Smooth muscle
- C. Skeletal muscle
- D. Striated muscle
Correct Answer: B
Rationale: Smooth muscle is the correct answer. It is found in the walls of hollow organs like the stomach and intestines, where it performs involuntary contractions to move substances through these organs. Cardiac muscle, found in the heart, is responsible for pumping blood. Skeletal muscle is attached to bones and involved in voluntary movements. Striated muscle is a term often used interchangeably with skeletal muscle, which is responsible for voluntary movements but not typically found in the walls of hollow organs like the stomach and intestines.
What phenomenon is responsible for the creation of rainbows?
- A. Reflection only
- B. Diffraction
- C. Refraction and reflection
- D. Polarization
Correct Answer: C
Rationale: Rainbows are created by both refraction and reflection of sunlight within water droplets in the atmosphere. When sunlight enters a water droplet, it is refracted, then internally reflected, and finally refracted again as it exits the droplet. This process causes the separation of light into its component colors and the formation of a rainbow. Choice A is incorrect because rainbows are not solely formed by reflection. Choice B, diffraction, is not the primary phenomenon responsible for rainbows. Choice D, polarization, is not directly involved in the creation of rainbows. Therefore, the correct answer is C.
Which element is used in fluorescent lamps and emits ultraviolet light when excited?
- A. Mercury
- B. Neon
- C. Argon
- D. Krypton
Correct Answer: A
Rationale: Mercury is the correct element used in fluorescent lamps to emit ultraviolet light when excited. When an electric current passes through the mercury vapor inside the lamp, it generates ultraviolet (UV) light. This UV light then excites the phosphors coated on the inner surface of the lamp, causing them to emit visible light. Neon, argon, and krypton are not commonly used in fluorescent lamps for this purpose. Neon is primarily used in neon signs, argon is used in incandescent and fluorescent bulbs for inertia gas, and krypton is mainly used in certain types of specialized light bulbs for its specific properties.