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