Equation: 3Cu(s) 8HNO3(aq) --> 2NO(g) 3Cu(NO3)2(aq) 4H2O(l) In the above reaction, the element oxidized is , the reducing agent is and the number of electrons transferred from reducing to oxidizing agent in the equation, as written, is .

1. Cu

2. Cu

3. 2 electrons.

Explanation:

Step 1:

The equation for the reaction is given below:

3Cu(s) + 8HNO3(aq) -> 2NO(g) 3Cu(NO3)2(aq) + 4H2O(l)

Step 2:

Determination of the change of oxidation number of each element present.

For Cu:

Cu = 0 (ground state)

Cu(NO3)2 = 0

Cu + 2( N + 3O) = 0

Cu + 2(5 + (3 x -2)) =0

Cu + 2 (5 - 6) = 0

Cu + 2(-1) = 0

Cu - 2 = 0

Cu = 2

The oxidation number of Cu changed from 0 to +2

For N:

HNO3 = 0

H + N + 3O = 0

1 + N + (3 x - 2) = 0

1 + N - 6 = 0

N = 6 - 1

N = 5

NO = 0

N - 2 = 0

N = 2

The oxidation number of N changed from +5 to +2

The oxidation number of oxygen and hydrogen remains the same.

Note:

1. The oxidation number of Hydrogen is always +1 except in hydride where it is - 1

2. The oxidation number of oxygen is always - 2 except in peroxide where it is - 1

Step 3:

Answers to the questions given above

From the above illustration,

1. Cu is oxidize because its oxidation number increased from 0 to +2 as it loses electron.

2. Cu is the reducing agent because it reduces the oxidation number of N from +5 to +2.

3. The reducing agent i.e Cu transferred 2 electrons to the oxidising agent HNO3 because its oxidation number increase from 0 to +2 as it loses its electrons. This means that Cu transfer 2 electrons.

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.