Waec Physics 1999 Past Questions and Answers

Question 41:

• WAEC 1999

Bohr’s atomic model proves most successful for the explanation of the. I. structure of the hydrogen atom; II. line spectra of the hydrogen atom; III. Multi-electron atoms. Which of the statements above is/are correct?

A. I only
B. II only
C. I and II only
D. I and III only

Question 42:

• WAEC 1999

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

Question 43:

• WAEC 1999

Which of the transitions will produce the emission of highest frequency?

A. V
B. IV
C. III
D. II

Question 44:

• WAEC 1999

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

Question 45:

• WAEC 1999

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