። EXOTHERMIC REACTIONS: Those reactions in which heat is evolved, they are known as Exothermic Reactions. For example,
Burning of natural gas (CNG) and respiration are exothermic reactions.
CH⁴ +20² → CO² +2H²0 +heat [Combustion of Natural gas]
C⁶H¹²O⁶+ 602 → 6CO²+ 6H²0 + heat [Respiration]
CaO + H²O ---→Ca(OH)2 (slaked lime)
[Reaction of Quick lime with water]
LET US SEE WHAT WE HAVE LEARNT :
1. Quick lime and slaked lime are
(a) Ca(OH)2 and Cao (b) CaO and CaCO3 (c) CaO and Ca(OH)2
Answer 1 Ca(OH)2 and Cao.
2.Put a sign on the reaction, which is not an exothermic, of the following
(a) Respiration reaction (b) Dipping a piece of iron in water (c) Burning of candle.
Answer 2 Dipping a piece of iron in water.
3.Which one of the following is not an example of a combination reaction ?
(a) 2H²0 +O² ---→ 2H²O
(b)AgNO³ + NaCl → AgCl + NaNO³
(c) 2Mg + O² → 2MgO
Answer 3 AgNO³ + NaCl → AgCl + NaNO³.
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