| 71 | The carrier waves used for the radio transmission have frequency upto | 30 KHz |
| 72 | Detergents dissolved in water help in cleaning clothes by | Reducing the surface tension of water |
| 73 | Wisdom teeth normally grow between the age of | 17-35 |
| 74 | Which one of the following sets of colour combinations is added in colour vision in TV? | Red, green and blue |
| 75 | A lake starts freezing because of the cold atmosphere. It will first freeze | At the top surface |
| 76 | A balanced diet contains | Food nutrients for growth and maintenance |
| 77 | According to the definition of 1 KWh, a 100 watt bulb consumes one unit of electricity in | 10 hours |
| 78 | In railway tracks, a small gap is left between the rails | To allow for the expansion during heat |
| 79 | Acid rain contains high levels of | Sulphuric and nitric acids |
| 80 | The Green House Effect is caused by an excess of | Carbon dioxide |