Waec Physics 2000 Past Questions and Answers

Question 46:

• WAEC 2000

The half life of a radioactive substance is 14 days. If 48g of this substance is stored, after how many days will 1.5g of the original substance remain?

A. 84 days
B. 70 days
C. 56 days
D. 40 days

Question 47:

• WAEC 2000

A material of mass 1.0 x 10^-2kg undergoes a fission process which decreases its mass by 0.02 percent. Calculate the amount of energy released in the process. (c = 3.0 x 10⁸ms^-1)

A. 1.8 x 10²⁰J
B. 1.8 x 10¹³J
C. 1.8 x 10¹¹J
D. 1.8 x 10¹⁰J

Question 48:

• WAEC 2000

Absorption line spectra exhibited by atoms is a result of

A. Change in the kinetic energy of a movimg atom
B. Instability of the nucleons
C. Excitation of an electron in the atom
D. Transition of an electron from a higher to a lower energy level

Question 49:

• WAEC 2000

In which of the following transitions is the largest quantum of energy liberated by an hydrogen atom when the electron changes energy levels? [n is the quantum number]

A. N = 2 to n = 1
B. N = 1 to n = 2
C. N = 2 to n = 3
D. N = 3 to n = 2

Question 50:

• WAEC 2000

A proton of wavelength \(\lambda_o\) is emitted when an electron in an atom makes a transition from a level of energy 2E_{[/sub]. If the electron transits from \(\frac{4}{3}E_k\) to E[sub]} level, determine the wavelength of the photon that would be emitted

A. 3\(\lambda_o\)
B. 2\(\lambda_o\)
C. \(\frac{3}{4}\)\(\lambda_o\)
D. \(\frac{1}{3}\)\(\lambda_o\)