17. Which of the following graphs shows how the activity of a sample varies with time?

radioactive decay curves x 4

18. Using the correct graph above, what is the half-life of this isotope?

A). 2 days
B). 4 days
C). 6 days
D). 8 days
19. A sample of 16g of radioactive substance X has a half-life of 2 hours. What percentage of the sample is left after 6 hours?

 
A). none
B). 12.5%
C). 25%
D). 33.3%
20. How old is the sample when only 1 gram of substance X remains?

A). 4 hours
B). 8 hours
C). 16 hours
D). 32 hours
21. What has happened to the other 15 grams of substance X?

A). It has changed into a different element.
B). It has all radiated away.
C). It is still there but now has been ionised.
D). It has evaporated.

22. Radiation can be detected using ...

A) an oscilloscope
B) a geiger counter
C) a potometer
D) an ionisometer
23+24: Radioactive elements are used in medicine to trace medical conditions. medical tracer skeleton
Which of the following half-lives would be most suitable for a tracer used in a patient?

A).  3 minutes
B).  3 hours
C).  3 days
D).  3 years
24. What form of radiation should it emit?

A). alpha
B). beta
C). gamma
D). any of these

25+26: These questions are about radioactive substances and safety. nuclear power graphic

25. Radioactivity can be used to sterilise medical equipment. Which of these statements is true?

A). The equipment must be contaminated with radioactive isotopes.
B). The equipment must be irradiated by ionising radiation.
C). The equipment must be contaminated and irradiated by radioactive isotopes.
D). The equipment must not be exposed to any isotopes or ionising radiation in this process.

26. Which of these statements is not true?

A). Alpha particles cause tissue damage if emitted inside the body.
B). Gamma rays are less ionising than alpha but can pass through the body and damage internal organs. 
C). All 3 types of radiation can cause cancer.
D). Beta particles are not considered a health risk as they are less ionising and cannot reach internal organs from outside the body.

27. When Uranium decays it emits an alpha particle, forming an isotope of Thorium. Which of the following decay equations is correct?

A.  
238
 U    →  
232
 Th 
+
2
 α 
92
90
2

B.  
238
 U    →  
236
 Th 
+
2
 α 
92
90
2

C.  
238
 U    →  
234
 Th 
+
4
 α 
92
90
2

D.  
238
 U    →  
232
 Th 
+
4
 α 
92
90
2
28. What change takes place to an atom during beta decay?

A). A proton changes into a neutron.
B). A proton changes into an electron.
C). An electron changes into a neutron.
D). A neutron changes into a proton.
29.
14
 C (carbon - 14) is radioactive.
6
It decays into nitrogen through beta decay. What isotope remains?
  
A.  
14
 N
7
B.  
15
 N
7
C.  
13
 N
6
D.  
14
 N
6

30. In this decay equation, what are the missing numbers x and y?

 
24
 Na →
24
 Mg
+
y

ß

11
x
-1
  • A. x=10, y=1
  • B. x=10, y=0
  • C. x=12, y=1
  • D. x=12, y=0