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Answer 1

Answer:

12. X = CaO

    Y = $CO_{2}$

    Z = $CaCO_{3}$

Reaction --> CaO +$CO_{2}$ = $CaCO_{3}$

13.A reaction in which two or more reactants combine to form a single product is known as a combination reaction. Combination reaction is also known as a synthesis reaction. Examples of combination reaction.

2Na + Cl2 → 2NaCl. C + O2 → CO2.

Calcium oxide reacts with water to produce calcium hydroxide.

14. An exothermic reaction is defined as a reaction that releases heat and has a net negative standard enthalpy change.

Examples include any combustion process, rusting of iron, and freezing of water.

15. Decomposition reactions are processes in which chemical species break up into simpler parts. Usually, decomposition reactions require energy input. For example, a common method of producing oxygen gas in the laboratory is the decomposition of potassium chlorate (KClO3) by heat.

16. Endothermic reactions are chemical reactions in which the reactants absorb heat energy from the surroundings to form products.

When ammonium chloride (NH4Cl) is dissolved in water, an endothermic reaction takes place.

17. That salt was iron sulphate. Iron sulphate(FeSO₄) produces a colourless suffocating gas and leaves behind a brown residue.

FeSO₄ (s)(green)   ⇒ Fe₂O₃ (s) (brown)  +  SO₂ (g)(white) +  SO₃(g)

X = FeSO₄

Y = SO₂

Z =  Fe₂O₃

18. The Gas formed on heating limestone is Carbon dioxide. When this gas is passed through lime water, it forms Calcium Carbonate or limestone which turns milky.

Reaction for the above is-

When Limestone is heated,

   CaCO3 →CaO+CO  2

X = CaO

Y = CO 2

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