Answer:
Explanation:
The net force on electron is electrostatic force between electron and proton in the nucleus .
Fc = 
This provides the centripetal force for the circular path of electron around the nucleus .
Centripetal force required = 
So



Answer: Elements in the last period are radioactive.
Explanation:
Answer : The balanced reduction half-reaction is:

Explanation :
Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.
Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.
Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.
The given balanced redox reaction is :

The half oxidation-reduction reactions are:
Oxidation reaction : 
Reduction reaction : 
In order to balance the electrons, we multiply the oxidation reaction by 2 and reduction reaction by 3 and then added both equation, we get the balanced redox reaction.
Oxidation reaction : 
Reduction reaction : 
The balanced redox reaction will be:

Thus, the balanced reduction half-reaction is:

Answer:
The electrochemical phenomenon of rusting of iron can be described as : At Anode: Fe (s) undergoes oxidation to releases electrons. Electrons released at anode move to another metal and reduce oxygen in presence of H+. It is available from H2CO3 formed from the dissolution of CO2 from air into water.