Which of the following changes requires an oxidizing agent?
o2 yields 2o2-
so3 yields so42-
2f- yields f2
mno2 yields mn2+

Answer : The correct option is,

Explanation :

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In the oxidation reaction, the oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Oxidizing agent : It is defined as the substance which has ability to oxidize the other substances by gaining electrons.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In the reduction reaction, the oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

Reducing agent : It is defined as the substance which has ability to reduce the other substances by losing electrons.

From the given options, we conclude that

(1)

(2)

(3)

The reaction 1, 2 and 3 shows the reduction reaction. So, it requires a reducing agent.

(4)

The reaction 4 shows the oxidation reaction. Therefore, it requires an oxidizing agent.

Therefore, the correct option is,

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml