The energy exchanges between space,the atmosphere and the Earth surface produce Weather and Climate
The correct answer is
<span>3. Organic Chemistry.....</span>
-20.16 KJ of heat are released by the reaction of 25.0 g of Na2O2.
Explanation:
Given:
mass of Na2O2 = 25 grams
atomic mass of Na2O2 = 78 gram/mole
number of mole = 
= 
=0. 32 moles
The balanced equation for the reaction:
2 Na2O2(s) + 2 H2O(l) → 4 NaOH(aq) + O2(g) ∆Hο = −126 kJ
It can be seen that 126 KJ of energy is released when 2 moles of Na2O2 undergoes reaction.
similarly 0.3 moles of Na2O2 on reaction would give:
= 
x = 
= -20.16 KJ
Thus, - 20.16 KJ of energy will be released.
Answer: option a and d
Explanation:
Option A- Benzene undergoes substitution reaction
Example : benzene reacts with chlorine to form chlorobenzene, in the presence of Iron
(iii) chloride as a catalyst
C6H6 + Cl2 ---> C6H5Cl + HCl
Option D- Benzene also undergoes addition reaction
Example: benzene reacts with hydrogen , in the presence of nickel as a catalyst to form
cyclohexane
C6H6 + 3H2 ---> C6H12
Reasons why Option B isn't the answer
Although benzeme has degree of unsaturation but it's not five degree of unsaturation.
Benzene has 6 carbon atoms and 4 degrees of unsaturation (1 ring and 3 double
bonds).
If you work backwards and double the degrees of unsaturation you have 8 degrees of
unsaturation instead of 5.
Option C - Benzene isn't a saturated hydrocarbon
Answer: a) 
b) 1 mole of
is produced.
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The skeletal equation is:

The balanced equation will be:

Thus the coefficients are 2, 3 , 10 , 4 , 3 , 2 and 5.
b) Oxidation: 
Reduction: 
Net reaction: 
When 1 mole of
is produced, 1 mole of
is produced.