1. Oxygen cannot be further subdivided into simpler substances by any physical or chemical means. Therefore, it is _______.   a mixture   an element   a compound   Hint Half-n-half Clue   2. Copper sulfate solution can be further subdivided into simpler substances by physical (mechanical) means. Therefore, it is _______.   an element   a compound   a mixture   Half-n-half Clue   3. Which of the following is a compound?   Sodium sulfide   Sodium   Sodium sulfide solution   Half-n-half Clue   4. Which of the following is a pure substance made up of two or more types of atoms or elements?   Element   Mixture   Compound   Half-n-half Clue   5. Which of the following is a mixture?   Potassium   Potassium carbonate   Potassium carbonate solution   Half-n-half Clue   6. Copper sulfate can be further subdivided into simpler substances by chemical means only. Therefore, it is _______.   a mixture   an element   a compound   Half-n-half Clue   7. Which of the following is a pure substance made up of one type of atoms?   Element   Compound   Mixture   Half-n-half Clue