Nokea
Which element is considered a noble gas?
- A. Oxygen
- B. Neon
- C. Hydrogen
- D. Argon
Correct Answer: B
Rationale: The correct answer is 'Neon.' Noble gases are a group of elements with very low reactivity. Neon is one of these elements, known for its stable and unreactive nature. Oxygen, hydrogen, and argon do not belong to the noble gas group. Oxygen is a reactive non-metal, hydrogen is a non-metal and the first element in the periodic table, and argon is a noble gas like neon but not the correct answer in this case.
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What type of reaction occurs when an acid and a base react to form water and salt?
- A. Neutralization reaction
- B. Decomposition reaction
- C. Combustion reaction
- D. Redox reaction
Correct Answer: A
Rationale: A neutralization reaction is the correct answer. In this type of reaction, an acid and a base combine to form water and salt. The acid donates a proton (H+) to the base, forming water, while the remaining ions combine to form a salt. This reaction results in the neutralization of both the acid and the base, hence the name 'neutralization reaction.'
Choice B, decomposition reaction, is incorrect because it refers to a reaction where a compound breaks down into simpler substances.
Choice C, combustion reaction, is incorrect as it involves a substance reacting with oxygen to produce heat and light.
Choice D, redox reaction, is incorrect because it involves the transfer of electrons between reactants.
Which state of matter has a definite volume but takes the shape of its container?
- A. Gas
- B. Liquid
- C. Solid
- D. Plasma
Correct Answer: B
Rationale: The state of matter that has a definite volume but takes the shape of its container is a 'Liquid.' Liquids have a fixed volume but can change their shape to fit the container they are in. This property distinguishes liquids from solids, which have both a definite shape and volume, and gases, which do not have a fixed volume or shape. Therefore, the correct answer is 'Liquid.'
Choice A, 'Gas,' is incorrect because gases do not have a definite volume or shape. Choice C, 'Solid,' is incorrect as solids have a definite shape and volume. Choice D, 'Plasma,' is incorrect because plasma is a state of matter where atoms have been ionized and do not have a fixed volume or shape.
What is the name for the horizontal rows of the periodic table?
- A. groups
- B. periods
- C. families
- D. sets
Correct Answer: B
Rationale: In the periodic table, 'periods' are the horizontal rows. Each period corresponds to the energy level occupied by the elements in that row. The other terms mentioned, such as groups, families, and sets, are not used to describe the horizontal rows but rather refer to different aspects of the periodic table organization. 'Groups' are the vertical columns, 'families' are groups of elements with similar properties, and 'sets' is a more generic term not specifically used in the context of the periodic table.
How can water be boiled at room temperature?
- A. By lowering the pressure
- B. By increasing the pressure
- C. By decreasing the volume
- D. By raising the boiling point
Correct Answer: A
Rationale: The boiling point of water is directly affected by pressure. By lowering the pressure, water can boil at a lower temperature, even at room temperature. This occurs because at lower pressures, the molecules of water have less resistance to escaping into the vapor phase, thus enabling boiling to occur at lower temperatures. Choices B, C, and D are incorrect because increasing the pressure, decreasing the volume, or raising the boiling point would actually require higher temperatures to boil water rather than achieving boiling at room temperature.
What is the name of the phase change from liquid to gas?
- A. Condensation
- B. Sublimation
- C. Evaporation
- D. Melting
Correct Answer: C
Rationale: The correct answer is 'Evaporation.' This phase change occurs when a liquid turns into a gas. During evaporation, molecules gain enough energy to break free from the liquid phase and enter the gas phase, without the need for the liquid to reach its boiling point. Choice A, 'Condensation,' is the opposite phase change where gas turns into a liquid. Choice B, 'Sublimation,' is the phase change from solid directly to gas, skipping the liquid phase. Choice D, 'Melting,' is the phase change from solid to liquid.