1999 - WAEC Physics Past Questions and Answers - page 5
41
The diagram above illustrates the energy transitions of five electrons of an atom. Which of the transitions will produce the emission of longest wavelength?
A
I
B
II
C
III
D
IV
correct option: a
Users' Answers & Comments42
Which of the transitions will produce the emission of highest frequency?
A
V
B
IV
C
III
D
II
correct option: a
Users' Answers & Comments43
I. All elements emit and absorb characteristic spectra. II. Spectral analysis is an important method of identifying environmental pollutants. III. The chemical composition of stars could be determined using spectral analysis. Which of the statements above are correct?
A
I, II and III
B
II and III only
C
I and III only
D
I and II only
correct option: a
Users' Answers & Comments44
A metal has work function of 4.375 eV Calculate its threshold frequency. (h = 6.6 x 10-34Js; 1eV = 1.6 x 10-19J)
A
2.01 X 1015Hz
B
1.06x1015Hz
C
6.30 x 1014Hz
D
1.60 x 1014Hz
correct option: b
Users' Answers & Comments45
The half-life of a radioactive substance is
A
its average life time
B
one-half the value of its decay constant.
C
the length of time needed by the substance to decay completely
D
the length of time during which the activity of the substance reduces by 50%.
correct option: d
Users' Answers & Comments46
The half-life of a radioactive element is 5 Calculate its decay constant
A
0.113s-1
B
0.436 s-1
C
0.139 s-1
D
0.193 s-1.
correct option: c
Users' Answers & Comments47
A sheet of paper is placed in the path of the following radiations: I. Alpha particles II. Beta particles III. Gamma rays. Which of the radiations will pass through the sheet of paper?
A
I only
B
II only
C
I and II only
D
II and III only
correct option: d
Users' Answers & Comments48
Which of the following are the essential parts of an atomic bomb?
A
Uranium and neutrons
B
Radium and polonium
C
Nitrogen and neutrons
D
ranium and α - particles.
correct option: a
Users' Answers & Comments49
Which of the following is not a safety precaution in a nuclear station?
A
Radioactive materials are stored in glass casings
B
Radioactive materials are handled with remote-controlled tongs
C
Technicians in nuclear stations wear radio-sensitive badges which are checked regularly.
D
Radioactive materials are kept in thick-walled lead containers
correct option: b
Users' Answers & Comments