1. What gas is evolved when HCl is poured on marble chips?   Calcium Carbonate   Carbon Dioxide   Hydrogen   Hydrogen Peroxide   Hint Half-n-half Clue   2. Nitrogen constitutes nearly __ % of the atmosphere.   42   21   79   57   Half-n-half Clue   3. A space that contains no air or any gas is known as   Pressurized Cabin   Vacuum   Hollow   Bubble   Half-n-half Clue   4. Which of the following is not a constituent of the atmosphere?   Carbon Dioxide   Oxygen   Aluminum   Nitrogen   Half-n-half Clue   5. Air is   An Alloy   An Element   A Mixture   A Compound   Half-n-half Clue   6. What is the name given to the respiratory holes on the surface of a leaf?   Pits   Chlorophyll   Stomata   Tendrils   Half-n-half Clue   7. The lower, dense region of the atmosphere is known as   Ionosphere   Hydrosphere   Troposphere   Stratosphere   Half-n-half Clue