Question 216:

• JAMB 1982

Why does a piece of cork float on water?

A. There is no upthrust on it when completely immersed in water
B. The upthrust on it when completely immersed in water is greater than its weight in air
C. The upthrust on it when completely immersed in water is less than its weight in air
D. Its specific gravity is greater than that of water
E. Its specific gravity is the same as that of water

Question 217:

• JAMB 1982

A rod of length 10cm is heated through 100^oC and its final length is 10.26cm. What is the co-efficient of linear expansion of the rod?

A. 0.026 per degree centigrade
B. 0.00026 per degree centigrade
C. 0.26 per degree centigrade
D. 1.0026 per degree centigrade
E. 0.0026 per degree centigrade

Question 218:

• JAMB 1982

If the refractive index of a medium is V2, what is the critical angle?

A. 45^o
B. 50^o12'
C. 56^o25'
D. 75^o
E. 90^o

Question 219:

• JAMB 1982

In copper plating, a current of 0.5A is allowed for cathode area of 100cm². If this current is maintained constant for 100 minutes, the thickness of the copper deposited will be approximately (the electrochemical equivalent of copper = 0.0003g/^oC, density of copper = 10^-4g/cm³ )

A. 10^-2mm
B. 10^-3mm
C. 10^-4mm
D. 10^-5mm
E. 10^-6mm

Question 220:

• JAMB 1982

As a positively charge rod is brought nearer to the top cap of a positively charged gold leaf electroscope, the divergence of the leaves will

A. Decrease to zero
B. Steadily increase
C. Decrease to zero and then increase
D. Remain constant
E. Increase to a maximum and then decrease