Question

Determine the amount of  required to provide a source of -particles of 5 millicurie strength. The half-life of Po is 138 days. The Avogadro’s number is 

Solution

Correct option is

The required strength (rate of -emission) of the source is  

        

                               

The decay constant is  

        

           

           

Let N be the number of atoms in the sample of strength  disintegration/s. Then  

        

   

            

            

By the definition of Avogadro’s number,  atoms of  has a mass of 210 g. 

  

                                                    .

SIMILAR QUESTIONS

Q1

The half-life of radius is 1600 years. After how many years 25% of a radium block remains undecayed?

Q2

The half-life of polonium is 140 days. In what time will 15 g of polonium be disintegrated out of its initial mass of 16 g?

Q3

The activity of a radioactive element reduces to th of its original value in 30 years. Find the half-life and the decay constant of the element.

Q4

The half-life of thorium-X is 3.64 days. After how many days will 0.1 of the mass of a sample of the substance remain undecayed?

Q5

How much of 5.00 gram of polonium will decay in one year? The half-life of polonium is 138 days.

  

Q6

The half-life of a radioactive substance is  against . Calculate the decay rate for  atoms of the substance.

Q7

The half-life of  against . Calculate the activity of 1 g sample of . Avogadro’s number is .

Q8

The half-life of  is 28 years. How much is the disintegration rate of 15 mg of this isotope? The Avogadro’s number is .

Q9

1 g of particles per second. Find its half-life and average life. Avogadro’s number is .

Q10

The disintegration rate of a certain radioactive sample at any instant is 4750 disintegrations per minute. 5 minute after, the rate becomes 2700 disintegrations per minute. Calculate the half-life of the sample. .