Question

The half life of a certain radio isotope is 10 minutes. The number of radioactive nuclei at a given instant of time is 108. Then the number of radioactive nuclei left 5 minutes later would be

Solution

Correct option is

.

Therefore 5 minutes  of half-life. It follows that the number of nuclei left after 5 minutes will be  

                

                  .

SIMILAR QUESTIONS

Q1

In an atom there are p photons, n neutrons and e electrons. For atoms of small mass, the relation between pn and e is   

Q2

Cal to protons ever attract each other?

Q3

How much energy is released when one amu is wholly converted into energy?

Q4

In the equation     

           ,  

The correct symbol for X is

Q5

The kinetic energy of a 300 K thermal neutron is

Q6

The energy released by the fission of one uranium atom is 200 MeV. The number of fissions per second required to produce 3.2 W of power is

Q7

The binding energy of deuteron  is 1.15 MeV per nucleon and an alpha particle  has a binding energy of 7.1 MeV per nucleon. Then in the reaction 

             

the energy Q released is 

Q8

What is the rest mass energy of an electron?

Q9

After two hours  of the initial amount of a certain radioactive isotope remains undecayed. The half life of the isotope is  

Q10

The half life of Pa – 218 is 3 minutes. What mass of a 16 g sample of Pa – 218 will remain after 15 minutes?