IB Past Paper Question Analysis Topic: Chemistry - Acids, Bases and Salts
(1) A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains:
D. K CL
Crushed egg shell has composition CaCO3 reacts with acid and gives gas CO2 which turns lime water (Ca(OH)2) milky by producing CaCO3 again. The acid in given options is HCl.
Ca (OH)2+C02→CaC03 + H2O
(2) Which one of the following types of medicines is used for treating indigestion?
C. Because antacid is a class of drug which neutralises the excessive acid produced in the stomach. This drug is used to treat acidity. For example: milk of magnesia.
(3) Why does distilled water not conduct electricity, whereas rain water does?
Distilled water is pure form of water which do not contain any solute in it. Therefore it cannot conduct electricity because it does not contain ions while rain water contains dissolved salts and acides which dissociates in ions and conducts electricity.