Nokea
In the chemical reaction CH₄ + 2O₂ → CO₂ + 2H₂O, what are the reactants?
- A. CHâ‚„ and Oâ‚‚
- B. COâ‚‚ and Hâ‚‚O
- C. Both
- D. None of the above
Correct Answer: A
Rationale: The correct answer is 'A: CHâ‚„ and Oâ‚‚.' Reactants are the substances that undergo a change to form the products in a chemical reaction. In the given reaction, CHâ‚„ (methane) and Oâ‚‚ (oxygen) are the reactants, as they transform into COâ‚‚ and 2Hâ‚‚O, which are the products. Therefore, the correct answer is A.
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Will solids always sink in liquids?
- A. True, a solid is hard, and liquids are not.
- B. True, solids are heavier than liquids.
- C. False, solids have a smooth surface so they will float.
- D. False, it depends on the density of the solid and liquid.
Correct Answer: D
Rationale: Solids will not always sink in liquids. Whether a solid sinks or floats in a liquid depends on the relative densities of the solid and the liquid. If the density of the solid is greater than that of the liquid, it will sink. If the density of the solid is less than that of the liquid, it will float. Therefore, it is incorrect to state that solids will always sink in liquids without considering their respective densities. The weight or hardness of the solid and the smoothness of its surface do not determine whether it will sink or float in a liquid. The critical factor is the density relationship between the solid and the liquid.
Will solids always sink in liquids?
- A. True, because solids are hard while liquids are not.
- B. True, because solids are heavier than liquids.
- C. False, because solids have a smooth surface, so they will float.
- D. False, it depends on the density of the solid and liquid.
Correct Answer: D
Rationale: The statement 'solids will always sink in liquids' is not always true. Whether a solid sinks or floats in a liquid depends on the relative densities of the solid and the liquid. If the density of the solid is greater than the density of the liquid, the solid will sink. Conversely, if the density of the solid is less than the density of the liquid, the solid will float. Therefore, the correct answer is 'False, it depends on the density of the solid and liquid.'
How are chemical equations typically written?
- A. Products → Reactants
- B. Reactants → Products
- C. Reactants + Reactants
- D. Products + Reactants
Correct Answer: B
Rationale: Chemical equations are typically written with reactants listed on the left side of the arrow and products on the right side. This convention signifies the progression of reactants transforming into products during a chemical reaction. Therefore, the correct way chemical equations are typically written is 'Reactants Ć’ Products.'
At very high temperatures, which state of matter is most commonly present?
- A. Solid
- B. Liquid
- C. Gas
- D. None of the above
Correct Answer: C
Rationale: At very high temperatures, substances tend to exist in the gaseous state. This is because the high energy levels cause the particles to move more rapidly and break free from the solid or liquid state. The increased movement and energy lead to gases being commonly present at very high temperatures. Therefore, the correct answer is 'Gas.'
Arrange the following unknown fluids in the correct order of how they would separate in a beaker, listed from bottom to top, based on the given measurements.
- A. A, B, C
- B. A, C, B
- C. C, A, B
- D. B, A, C
Correct Answer: B
Rationale: To determine the order of separation in a beaker, we need to consider the densities of the fluids. Density (d) = mass (m) / volume (V). Comparing the densities of the fluids, we find: Fluid A: d = 2060g / 2000mL = 1.03 g/mL, Fluid B: d = 672g / 850mL = 0.79 g/mL, Fluid C: d = 990g / 1100mL = 0.90 g/mL. Since fluids separate in a beaker based on their densities (with the highest density sinking to the bottom), the correct order from bottom to top is B (highest density), then C, and finally A (lowest density). Therefore, the correct answer is A,C,B.