Engineering :: Heat Transfer

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121.

A piece of metal with a circular hole is heated. If the metal expands on heating the diameter of the hole will

A.	Increase	B.	Decrease
C.	Increase or decrease depending upon the diameter of the whole	D.	Increase or decrease depending on the kind of the metal

122.

What energy transformation takes place when ice is converted into water

A.	Heat energy to kinetic energy	B.	Kinetic energy to heat energy
C.	Heat energy to latent heat	D.	Heat energy to potential energy
E.	None of the above

123.

Unsaturated vapours

A.	Do not obey gas laws	B.	Fully obey gas laws
C.	Obey Boyle's law but not Charle's law	D.	Partly obey gas laws depending upon the degree of unsaturations

124.

Which one of the following is a very good insulator?

A.	A hard wood board	B.	A porcelain sheet
C.	An asbestos sheet	D.	Saw dust

125.

Oxygen boils at -183?C, this temperature is

A.	? 215?F	B.	? 227?F
C.	? 329?F	D.	? 361?F
E.	? 398?F

126.

Absolute zero is

A.	0?C	B.	0?F
C.	0?R	D.	0?K
E.	273?C

127.

The temperature reading taken using Centigrade and Fahrenheit thermometers are plotted on a graph -?C along X-axis, ?F along Y-axis. The shape of graph would be

A.	Straight line cutting an intercept on the positive Y-axis	B.	Straight line cutting an intercept on the positive X-axis
C.	Straight line cutting an intercept on the negative Y-axis	D.	Straight line cutting an intercept on the negative X-axis

128.

An isotherm is a graph

A.	Connecting points of equal temperature	B.	Showing pressure volume changes at constant temperature
C.	Connecting points of equal pressure	D.	Showing product of pressure and volume against pressure
E.	Constant temperature

129.

A sphere of radius 40 cm is lagged to a radius of 50 cm. The temperatures of outer and inner surfaces are 66?C and 235?C respectively. Thermal conductivity of logging per cm thickness is 0.7 kcal/m-hr?C. The rate of heat leakage will be

A.	1.49 kcal/hr	B.	298 kcal/hr
C.	398 kcal/hr	D.	500 kcal/hr
E.	666 kcal/hr

130.

Which of the following material has lest value of thermal diffusivity?

A.	Lead	B.	Mercury
C.	Aluminium	D.	Iron
E.	Rubber