| 81 | The speed of sound is | 343 meter per second |
| 82 | When water is filled in a bottle and is allowed to freeze, the bottle breaks because | Water expands on freezing |
| 83 | Steel is more elastic than rubber because | Ratio of stress to strain is more |
| 84 | A nuclear reactor harnesses nuclear energy by | Controlled chain reaction |
| 85 | As the amount of clay in a soil increases, its water retaining capacity | Increases |
| 86 | One kilowatt- hour is the amount of electrical energy that is consumed by 1000 watt appliance in | 1 hour |
| 87 | According to the definition of 1 KWh, a 100 watt bulb consumes one unit of electricity in | 10 hours |
| 88 | Quantity of fresh air required for a man is | 1000 cubic feet of air for every 20 minutes |
| 89 | Atmospheric pressure exerted on the earth is due to the | Gravitational pull |
| 90 | The function of haemoglobin is | To transport oxygen |