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13
Q:

Which of the following reactions are exothermic?

 

1)   C + O2  → CO22)  2Mg + O2  → 2MgO3)  CuSO4 + 5H2O  → CuSO4.5H2O4)  All the above

A) 1 B) 2
C) 3 D) 4

Answer:   D) 4



Explanation:

Here all the given options are Exothermic reactions. Exothermic reactions are those reactions which involves the release of heat.

 

Generally all the combining reactions are exothermic in nature.

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When formaldehyde and potassium hydroxide are heated , we get 

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The atoms of the elements having same atomic number but different mass number are called

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An atom has 7 electrons in its M - shell and contains 18 neutrons in its nucleus. What is its mass number

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