Chemistry
Poison used for killing rats is

Magnesium nitride (Mg3N2)
Zinc phosphide (Zn3P2)
Magnesium phosphide (Mg3P2)
Calcium phosphide (Ca3P2)

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Chemistry
Aqua regia is a 1 : 3 mixture, by volume, of

Conc. nitric acid and conc. sulphuric acid
Conc. sulphuric acid and conc. nitric acid
Conc. hydrochloric acid and conc. nitric acid
Conc. nitric acid and conc. hydrochloric acid

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