The maximum quantity of water needed per 50 kg of cement for M 15 grade of concrete is 28 liters. This is because the water-cement ratio for M 15 grade of concrete is 0.55, which means that for every 50 kg of cement, you need 28 liters of water.
Option A is incorrect because it is less than the required water-cement ratio. Option B is incorrect because it is the same as the required water-cement ratio. Option C is incorrect because it is more than the required water-cement ratio. Option D is incorrect because it is the same as Option C.
The water-cement ratio is an important factor in determining the strength of concrete. A higher water-cement ratio will result in a weaker concrete, while a lower water-cement ratio will result in a stronger concrete. The required water-cement ratio for M 15 grade of concrete is 0.55, which means that for every 50 kg of cement, you need 28 liters of water.
If you use less water than the required amount, the concrete will be too dry and will not be able to develop its full strength. If you use more water than the required amount, the concrete will be too wet and will be weak. It is important to use the correct amount of water to ensure that the concrete is strong and durable.