1. Fish breathe through   Nose   Skin   Lungs   Gills   Hint Half-n-half Clue   2. On burning charcoal which of the following gases is produced?   Nitrous Oxide   Oxygen   Carbon Dioxide   Hydrogen   Half-n-half Clue   3. Air is   An Alloy   An Element   A Compound   A Mixture   Half-n-half Clue   4. Which of the following is necessary for a substance to burn?   Gasoline   Hydrogen   Oxygen   Light   Half-n-half Clue   5. Air is a   Plasma   Gas   Solid   Liquid   Half-n-half Clue   6. What gas is evolved when HCl is poured on marble chips?   Hydrogen   Calcium Carbonate   Carbon Dioxide   Hydrogen Peroxide   Half-n-half Clue   7. Which of the following is NOT a noble gas?   Helium   Hydrogen   Argon   Krypton   Half-n-half Clue