131. What was the fissionable material used in the bombs dropped at Nagasaki (Japan) in the year 1945?
1. Sodium
2. Potassium
3. Plutonium
4. Iron
Option “3” is correct. ‘Fat Man’ was the code name for the type of bomb which was dropped on the Japanese city of Nagasaki by the United States of America. Plutonium was used as fissionable material in this bomb.
132. Sea seems blue due to-
1. Excess deepness
2. Reflection of sky and scattering of light by the drops of water
3. Blue colour of water
4. Upper layer of water
Option “2” is correct. “The ocean looks blue because red, orange and yellow (long wavelength light) are absorbed more strongly by water than is blue (short wavelength light). So when white light from the sun enters the ocean, it is mostly the blue that gets returned.
133. Soap bubble attains spherical shape due to ______.
Option “3” is correct. The Surface tension of water provides the necessary wall tension for the formation of bubbles with soap water. The tendency to minimize that wall tension pulls the bubbles into spherical shape.
134. Speed of light is maximum in _____.
1. Vacuum
2. Solids
3. Liquids
4. Gases
Option “1” is correct. In absolute vacuum, there are no particles, no material medium, nothing. So, there is no reflection, refraction, diffraction, etc. That is why it travels the fastest in vacuum.
135. What is the SI unit of electric current?
1. Newton
2. Joule
3. Ampere
4. Watt
Option “3” is correct. The SI unit for measuring an electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. Electric current is measured using a device called an ammeter.
136. If the force applied on the object is in the direction opposite to the direction of motion, the speed of the object __________.
1. Increases
2. Stops
3. Decreases
4. No effect
Option “3” is correct. If the force applied on the object is in the direction opposite to the direction of motion, the speed of the object decreases.
137. The SI unit of acceleration is _______________.
1. Meters per seconds squared
2. Meters per second
3. Seconds per meter
4. Seconds per meter squared
Option “1” is correct. The SI unit of acceleration is the meter per second squared.
138. Contact force is another name for _________.
1. Friction
2. Magnetic force
3. Electrostatic force
4. Muscular force
Option “1” is correct. Contact force is another name for Friction.
139. The ‘Choke’ used with a tube light is basically ____
1. An inductor
2. A capacitor
3. A transformer
4. A resistor
Option “1” is correct. The ‘Choke’ used with a tube light is basically an inductor.
140. What is the phenomenon which established the transverse nature of light?
