Question 271:

• JAMB 1983

1,000 identical drops of oil of density 500kgm^-3 have a total mass of 5 x 10^-4kg. One of the drops forms a thin film of area 0.5m² on water. The thickness of the film is

A. 2 x 10^-8m
B. 2 x 10^-9m
C. 2 x 10^-7m
D. 3 x 10^-9m
E. 2.8 x 10^-8m

Question 272:

• JAMB 1983

The total length of a spring when a mass of 20g is hung from its end is 14cm, while its total length is 16cm when a mass of 30g is hung from the same end. Calculate the unstretched length of the spring assuming Hooke's law is obeyed.

A. 9.33cm
B. 10.00cm
C. 10.66cm
D. 12.00cm
E. 15.00cm

Question 273:

• JAMB 1983

Which of the following statements is CORRECT? i. the mass number is equal to the total number of protons and electrons in an atom. ii. the atomic number is equal to the number of protons in an atom. iii. the number of electrons in an atom is equal to the total number of protons and neutrons in the nucleus.

A. I only
B. Ii only
C. Iii only
D. I and ii only
E. Ii and iii only

Question 274:

• JAMB 1983

A short response to time is obtained in liquid-in-glass thermometer when the

A. Bulb is large and thick-walled
B. Stem is long and thin
C. Bulb is small and thicked-walled
D. Liquid is of high density and the bore is large
E. Bulb is thin-walled and the liquid is a good conductor of heat

Question 275:

• JAMB 1983

A machine has a velocity ratio of 5. It requires a 50kg weight to overcome a 200kg weight. The efficiency is

A. 4%
B. 5%
C. 40%
D. 50%
E. 80%