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Chemistry · Class 9
Ammonia is a basic gas. Damp red litmus turns blue. The paper must be damp: the gas needs water to form OH- before the dye can change. Dry litmus shows no change, so the result is uncertain.
PracticeCarbohydrates are organic compounds that serve as a major source of chemical energy for living organisms.
PracticeIn the lab, CO2 is made from HCl + marble chips (CaCO3) -> CaCl2 + CO2 + H2O. Limewater is aqueous Ca(OH)2. The gas turns limewater milky because solid CaCO3 forms. That test distinguishes CO2 from O2, which does not milk limewater.
PracticeChlorine bleaches. Damp blue litmus goes red, THEN bleaches white. Damp is needed so the gas can dissolve and act. If you have only seen red so far, continue watching: the bleach is the part that names chlorine, not the red alone.
Practice