1071. Which gas is commonly used in balloons and airships ?

A. Hydrogen
B. Helium *
C. Carbon
D. Hydrogen suphide

1072. A slow-running pendulum clock can be speeded up by __________.

A. Increasing the lenght of the rod
B. Increasing the weight of the rod
C. Reducing the length of the rod *
D. Reducing the weight of the rod

1073. A man is standing on a weighing machine in a lift which is moving .The weighing maching will show minimum reading when, the lift is moving ________.

A. Upward with uniform speed
B. Downward with uniform accelaration
C. Upward with uniform acclaration
D. In a free fall due to failure of the lift machanism *

1074. The approximate intensity level of the sound which can caused damage to the ear drum is ________.

A. 20db
B. 60db
C. 100db *
D. 160db

1075. Fuse wire is made of _________.

A. 63% tin and 37% lead *
B. 63% lead and 37% tin
C. 63% tin and 37% alminium
D. 63% lead and 37% aluminium

1076. Which one of the following is the main culprit in the thinning of Ozone layer in the earth’s stratosphere ?

A. Carbon dioxide
B. Choloroflurocarbons
C. Nitrogen oxides *
D. Methane

1077. Steering of a car involves __________.

A. A single force
B. Two forces acting in the same direction.
C. Two forces acting along different lines and in opposite direction
D. A pair of forces acting along the same line and in opposite direction *

1078. The property by virtue of which metals can be beaten into thin sheets is known as __________.

A. Ductility
B. Malleability *
C. Conductivity
D. Density

1079. The sky appears blue because the earth’s atmosphere _________.

A. Scatters blue light
B. Reflects blue light *
C. Transmit blue light
D. Has actual blue cover

1080. The most abundant element in Earth’s crust is _________.

A. Silicon
B. Iron
C. Aluminium
D. Oxygen *