Nokea
The products of a reaction are CO2 and H2O. Which type of reaction is this most likely to be?
- A. Synthesis
- B. Decomposition
- C. Single replacement
- D. Combustion
Correct Answer: D
Rationale: The reaction products CO2 and H2O indicate the formation of carbon dioxide and water, which are typical products of a combustion reaction. Combustion reactions involve the rapid combination of a substance with oxygen, producing heat and light energy. In this case, the presence of CO2 and H2O suggests a combustion reaction where a hydrocarbon or organic compound has reacted with oxygen to form these products. Therefore, the correct answer is 'Combustion' (choice D) as it aligns with the formation of CO2 and H2O in this reaction scenario.
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A block on your desk acts as a paperweight with measurements of 3 cm by 4 cm by 6 cm. The block has a mass of 184.32 g. What is its density?
- A. 13,271.04 g/cm³
- B. 2.56 g/cm³
- C. 0.39 g/cm³
- D. None of the above
Correct Answer: B
Rationale: Density is calculated by dividing mass by volume. To find the volume of the block, multiply its dimensions (3 cm x 4 cm x 6 cm = 72 cm³). Dividing the mass (184.32 g) by the volume (72 cm³) gives a density of 2.56 g/cm³. Therefore, the correct answer is B.
A carbon atom with fewer neutrons than a neutral carbon atom is known as what?
- A. Isotope
- B. Ion
- C. Both are correct
- D. None of the above
Correct Answer: A
Rationale: The correct answer is 'Isotope.' An isotope is a variant of a chemical element that has the same number of protons but a different number of neutrons in its nucleus. In this scenario, a carbon atom with fewer neutrons than a neutral carbon atom represents a different isotope of carbon with a distinct atomic mass. The difference in neutron count does not alter the atom's charge, ruling out the possibility of it being an ion. Therefore, the appropriate term to describe this situation is 'Isotope.'
What is the term for the reactant that is entirely consumed in a reaction?
- A. limiting reactant
- B. reducing agent
- C. reaction intermediate
- D. reagent
Correct Answer: A
Rationale: The term for the reactant that is entirely consumed in a reaction is the limiting reactant. The limiting reactant is crucial in determining the maximum amount of product that can be formed as it is fully consumed in the reaction. The other choices, reducing agent, reaction intermediate, and reagent, do not specifically refer to the reactant that is completely consumed during the reaction process. Identifying the limiting reactant is essential for calculating the theoretical yield of a reaction and understanding the stoichiometry of the reaction.
Which of the following elements does not exist as a diatomic molecule?
- A. boron
- B. fluorine
- C. oxygen
- D. nitrogen
Correct Answer: A
Rationale: The correct answer is boron (A). Diatomic molecules consist of two atoms of the same element bonded together. Boron does not naturally form diatomic molecules in its elemental state. Fluorine (FÄ‚‚), oxygen (OÄ‚‚), and nitrogen (NÄ‚‚) are examples of elements that exist as diatomic molecules in their elemental forms. Boron typically forms covalent bonds with other elements but does not naturally exist as a diatomic molecule.
What is the atomic number?
- A. Number of neutrons
- B. Number of protons
- C. Number of electrons
- D. Number of isotopes
Correct Answer: B
Rationale: The atomic number is the number of protons in an atom's nucleus. It uniquely identifies an element and determines its chemical properties. The number of neutrons and electrons can vary in an atom, but the number of protons remains constant for a specific element. Therefore, the correct answer is the 'Number of protons' (Choice B).