Carry out transformations: calcium carbonate-calcium oxide-calcium hydroxide-calcium carbonate-calcium nitrate.

1) CaCO3 ↓ → CaO + CO2 ↑ (decomposition reaction; calcium carbonate, calcium oxide, carbon (IV) oxide);

2) CaO + H2O → Ca (OH) 2 ↓ (compound reaction; calcium oxide, water, calcium hydroxide);

3) Ca (OH) 2 + Na2CO3 → CaCO3 ↓ + 2NaOH (exchange reaction; calcium hydroxide, sodium carbonate, calcium carbonate, sodium hydroxide);

4) CaCO3 + 2KNO3 → Ca (NO3) 2 + K2CO3 (exchange reaction; calcium carbonate, potassium nitrate, calcium nitrate, potassium carbonate).

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