Question

The element strontium has many naturally occurring isotopes, some of which are unstable.
(a) Table 9.1 shows the half‑lives of four unstable isotopes of strontium.

       

(i) Fig. 9.1 shows a decay curve for one of the isotopes given in Table 9.1.

     

  Determine which isotope of strontium from Table 9.1 would give the data shown in Fig. 9.1.
  isotope …………………………………………………

  (ii) A scientist purchases a sample of a strontium isotope to use as a radioactive source in a series of experiments.
        The scientist estimates that the experiments will take three months to complete.
        Suggest which of the isotopes in Table 9.1 would be best for the scientist to purchase.
        Explain your suggestion.
         isotope ………………………………………………………………………
         explanation ………………………………………………………………..

(b) Place ticks (✓) in Table 9.2 to show the nature of a beta particle.

               

(c) The density of strontium is 2.6g/cm³ .
      A sample of strontium has a mass of 7.8g.
      Calculate the volume of the sample of strontium.
            volume = ………………………… cm³

▶️Answer/Explanation

Ans : 

9(a)(i) half-life calculated from graph ;
               strontium-82 ;

9(a)(ii) strontium-90 AND it will not need to be replaced for a long time/ will last for a long time / will not run out quickly/owtte ;

9(b) has a negative charge ;
          is affected by electric fields AND is affected by magnetic fields ;

9(c) (V=) m/ρ OR 7.8 / 2.6 ;
         (V=) 3.0 (cm³) ;