State whether the following statements are true or false. Correct the false statements.
(a) All substances are either acidic or basic.
(b) A compound if acidic will turn all indicators red.
(c) Lime water turns red litmus blue.
(d) Common salt dissolved in water turns blue litmus red.
(e) Phenolphthalein is a natural indicator.
(f) Calamine can be used to treat ant’s sting.
(g) Lemon water is basic in nature.
(a) False
Substances are classified into three categories. Those which are not acidic or basic comes under category of neutral substances.
(b) False
The fact given is not necessary. It actually depends on the nature of indicator. For example: phenolphthalein gives colourless mixture with acids.
(c) True
Lime water is basic in nature and hence turns red litmus to blue.
(d) False
The mixture of common salt with water is neutral and does not change color of litmus.
(e) False
Phenolphthalein is human made or artificial indicator.
(f) True
Reason: Calamine is basic in nature. Ant sting release methanoic acid in the sting area which creates irritation. Calamine being a base can undergo neutralization reaction with this acid to destroy its effect.
(g) False
Lemon water tastes sour and hence it is acidic in nature.