Question 311:

• JAMB 1984

A small steel needle is carefully floated on water in a beaker. When a few drops of kerosine are introduced into the water the needle sink. Which of the following statements correctly explain(s) the observation? i. there is tension on the water surface ii. kerosine reduces the density of water so that needle becomes denser than water iii. kerosine reduces the surface tension of water

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

Question 312:

• JAMB 1984

Which of the following statements describes an atom accurately? i. atoms of all elements are identical ii. an atom contains a nucleus and number of electrons iii. due to the electrons in the atom an atom is negatively charged iv. electrons in the atom move in circular orbits round the nucleus

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

Question 313:

• JAMB 1984

A particle moves in a circular orbit of radius 0.02m. If the speed of the particle is 0.88ms^-1, calculate its frequency in cycles per second

A. 2.0Hz
B. 7.0Hz
C. 8.8Hz
D. 14.0Hz
E. 17.6Hz

Question 314:

• JAMB 1984

Heat is supplied uniformly at the rate of 100W to 1.0 x 10^-2kg of a liquid for 20 seconds. If the temperature of the liquid rises by 5^oC, then the specific heat capacity of the liquid is

A. 2.0 x 10²Jkg^-1k^-1
B. 2.0 x 10²Jkg^-1
C. 4.0 x 10⁴Jkg^-1k^-1
D. 4.0 x 10⁴kg^-1
E. 8.4 x 10³Jkg^-1k^-1

Question 315:

• JAMB 1984

A given mass of an ideal gas occupies a volume V at a temperature T and under a pressure p. If the pressure is increased to 2p and the temperature reduced to \(\frac{1}{2T}\), then the percentage change in the volume of the gas is

A. 0%
B. 25%
C. 75%
D. 300%
E. 400%