Q1: The maximum vacuum created at the summit of a syphon is

ANS:B - 7.4 m of water

The maximum vacuum created at the summit of a siphon depends on the atmospheric pressure and the height of the water column in the siphon. The maximum theoretical vacuum that can be created by a siphon is limited by the atmospheric pressure. In an ideal situation, the maximum vacuum would be achieved when the siphon is at the top of its operation, meaning the water column is at its highest point. The maximum vacuum that can be achieved by a siphon is equal to the atmospheric pressure minus the pressure exerted by the water column. This is because the atmospheric pressure supports the water column in the siphon. Given that atmospheric pressure can support a water column approximately 10.3 meters high (equivalent to 1 atmosphere), and water has a density of about 1000 kg/m³, the maximum vacuum created at the summit of a siphon would be less than 10.3 meters of water. Therefore, among the options provided, the closest to this limit is 7.4 m of water.