1. Which of the following is not an allotrope of carbon?   Graphite   Diamond   Charcoal   Silk   Hint Half-n-half Clue   2. A substance that speeds up the rate of a chemical reaction without undergoing any change itself is known as a _______.   catalyst   counter ion   cation   nucleus   Half-n-half Clue   3. What is the combination of any substance with oxygen known as?   Reduction   Oxidation   Combustion   Hydrogenation   Half-n-half Clue   4. Which of the following is not a physical change?   Precipitation   Distillation   Decantation   Oxidation   Half-n-half Clue   5. Acids turn blue litmus paper _______.   pink   colorless   red   yellow   Half-n-half Clue   6. Lemon juice is _______ in nature.   basic   acidic   metallic   neutral   Half-n-half Clue   7. The two allotropes of phosphorus are _______ and _______.   Rhombic, Monoclinic   Alpha, Beta   Red, Yellow   Crystalline, Amorphous   Half-n-half Clue