Nokea
Which of the following is not an organic compound?
- A. Hâ‚‚O
- B. C₂H₆
- C. C₃H₇O₂
- D. None of the above
Correct Answer: A
Rationale: The correct answer is 'A: H₂O.' An organic compound is defined as a compound that contains carbon and hydrogen atoms bonded together. Choice A, H₂O (water), is composed of hydrogen and oxygen but lacks carbon, making it an inorganic compound. Choices B (C₂H₆) and C (C₃H₇O₂) both contain carbon and hydrogen, thus meeting the criteria for organic compounds. Therefore, the correct answer is A, H₂O, as it does not meet the definition of an organic compound due to the absence of carbon in its structure.
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Identify the reactants in the chemical reaction below: CH₄ + 2O₂ → CO₂ + 2H₂O
- A. CHâ‚„ and Oâ‚‚
- B. COâ‚‚ and Hâ‚‚O
- C. Both
- D. None of the above
Correct Answer: A
Rationale: Reactants in a chemical reaction are the initial substances that are transformed into products. In this reaction, CHâ‚„ (methane) and Oâ‚‚ (oxygen) are the reactants, as they are the starting materials that undergo a chemical change to form COâ‚‚ (carbon dioxide) and 2Hâ‚‚O (water). The equation clearly shows that CHâ‚„ and Oâ‚‚ are on the left side of the reaction arrow, indicating that they are the reactants. Therefore, the correct answer is A: CHâ‚„ and Oâ‚‚.
What is the pH of a solution with a pH of 7?
- A. Acidic
- B. Basic
- C. Neutral
- D. Positive
Correct Answer: C
Rationale: The correct answer is C: Neutral. A pH of 7 is considered neutral on the pH scale, which ranges from 0 to 14. A pH of 7 indicates a balance between acidic and basic properties in a solution, making it neither acidic nor basic. Values below 7 are acidic, above 7 are basic, and 7 is the midpoint representing neutrality. Therefore, a solution with a pH of 7 is neutral.
What is present in an emulsion?
- A. Water and salt
- B. Two or more immiscible liquids
- C. Any liquids
- D. All of the above
Correct Answer: B
Rationale: In an emulsion, two or more immiscible liquids are present. Immiscible liquids are those that do not mix together and form separate layers, such as oil and water. Emulsions are a type of colloid where one liquid is dispersed in another. Water and oil are a common example of an emulsion, where the two liquids do not mix naturally but can be forced to form a stable mixture with the help of an emulsifying agent.
What is the correct name for aqueous HI?
- A. hydroiodic acid
- B. hydrogen iodide
- C. iodine hydrogen
- D. hydroiodine acid
Correct Answer: A
Rationale: The correct name for aqueous HI is hydroiodic acid. In the naming of binary acids, the prefix 'hydro-' is combined with the root of the nonmetal element and the suffix '-ic acid'. Therefore, the correct systematic name for HI in aqueous solution is hydroiodic acid.
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.