1. If no more solute can be dissolved in a solvent at a given temperature then that solution is called _______.   an unstable solution   a saturated solution   a dispersed solution   a real solution   Hint Half-n-half Clue   2. Heat is liberated in _______ reactions.   exothermic   endothermic   all chemical   substitution   Half-n-half Clue   3. What is the combination of any substance with oxygen known as?   Oxidation   Reduction   Combustion   Hydrogenation   Half-n-half Clue   4. Which of the following is a chemical change?   Boiling of water   Rusting of iron   Dissolving of salt in water   Freezing of water   Half-n-half Clue   5. Which of the following is not a physical change?   Decantation   Oxidation   Precipitation   Distillation   Half-n-half Clue   6. The lead of a pencil mainly contains _______.   plastics   carbon black   lead   graphite   Half-n-half Clue   7. A substance that speeds up the rate of a chemical reaction without undergoing any change itself is known as a _______.   cation   nucleus   catalyst   counter ion   Half-n-half Clue