| 61 | The speed of sound is | 343 meter per second |
| 62 | The theory of Expanding Universe was first propounded by | Hubble |
| 63 | A slow-running pendulum clock can be speeded up by | Reducing the length of the rod |
| 64 | Washing soda in water behaves like | Acidic |
| 65 | To find the hidden secrets under the water, the ships and submarines use the | Sonar system |
| 66 | What is 'Stealth Technology'? | A coating which reduces the visibility of an aircraft on a radar |
| 67 | The property by virtue of which metals can be beaten into thin sheets is known as | Malleability |
| 68 | Which one of the following metals pollutes the air of a city having large number of automobiles? | Lead |
| 69 | The waves used for sending signals to the satellite from ground station are | Micro waves |
| 70 | Friction can be reduced by changing over from | Sliding to rolling |