The quantity of water required per 50 kg of cement for nominal mix concrete for M20 is:

1 A vessel contains 20 litres of acid. 4 litres of acid is taken out of the vessel and replaced by the same quantity of water. Next 4 litres of the mixture are with, drawn, and again the vessel is filled with the same quantity add left in the vessel with t 2 Two vessels contain mixtures of milk and water in the ratio of 8 : 1 and 1 : 5 respectively. The content of both of these are mixed in a specific ratio into a third vessel. How much mixture must be drawn from the second vessel to fill the third vessel (ca 3 A vessel contains a mixture of Grape, Pineapple and Banana juices in the respective ratio of 4 : 6 : 5. 15 litres of this mixture is taken out and 8 litres of grape juice and 2 litres of pineapple juice is added to the vessel. If the resultant quantity of 4 A liquid 'P' is $1\frac{3}{7}$ times as heavy as water and water is $1\frac{2}{5}$ times as heavy as another liquid 'Q' The amount of liquid ‘P' that must be added to 7 litres of the liquid ‘Q' so that the mixture may weigh as much as an equal volume of w 5 Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct?1. A a = new A();2. A a = new B();3. B b = new A();4. B b = new B();