It is not so easy to cut an apple with a blunt knife. But the same apple can be cut veryeasily with a sharp knife when the same force is applied. Why does this happen?1 The area of contact between the apple and the sharp knife is much lower, so the pressureapplied is higher for the same force.2 The force acting between the apple and the sharp knife is much higher than between the appleand the blunt knife.3 The weight of the blunt knife is more than that of the sharp knife and hence it becomes difficultto cut.4 The weight of the blunt knife is less than that of the sharp knife and hence it becomes difficult tocut.Science Test CLASS 8 SET NO 16Q: 23Air was blown into a balloon at the top of Mt. Everest and its mouth was tied with astring. What would happen to the size of the balloon if it was brought down to sealevel, say directly to Mumbai?1 It will become bigger for air pressure outside the balloon is now less than the pressure inside it.2 It will reduce in size as air pressure outside the balloon is now more than air pressure inside it.3 It will be the same as air pressure outside does not change much with altitude.4 Can't say, it depends on the weather in Mumbai, whether it is experiencing high or low pressure.Q: 24Four friends were discussing about the direction in which air in the atmosphere exertspressure.Here is what each one of them said.Rafe: Air in the atmosphere exerts pressure only upwards from the Earth.Jared: Air in the atmosphere exerts pressure only downwards towards the Earth.Devin: Air in the atmosphere exerts pressure in all directions.Shane: Air does not exert any pressure.Who among them is right?1 Rafe 2 Jared 3 Devin 4 Shane​