1. Lime water turns milky after carbon dioxide is passed through it.   True   False   2. When hydrogen peroxide acts on Manganese Dioxide, oxygen is produced.   True   False   3. Carbon dioxide is lighter than air.   True   False   4. Nitrogen constitutes nearly __ % of the atmosphere.   21   79   42   57   Hint Half-n-half Clue   5. Air is a   Solid   Gas   Plasma   Liquid   Half-n-half Clue   6. A hygroscopic substance is one which   Absorbs water   Releases air   Releases water   Absorbs air   Half-n-half Clue   7. Which of the following is necessary for a substance to burn?   Light   Oxygen   Gasoline   Hydrogen   Half-n-half Clue