Which of the following observations helps to determine whether a chemical reaction has taken place?

1 In an alloy, zinc and copper are in the ratio 1 : 2. In the second alloy, the same elements are in the ratio 2 : 3. If these two alloys be mixed to form a new alloy in which two elements are in the ratio 5:8, the ratio of these two alloys in the new allow 2 Direction: Read the following information carefully and answer the questions that follow: P, V, X, A, D, I, K and U set out for trip for different number of days such as 2, 8, 11, 5, 6, 4, 7 and 3, they go to the trip in the same order but the order of n 3 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 4 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 5 X and Y are two alloys which are prepared by mixing zinc and aluminium in the ratio of 1 : 4 and 11 : 8 respectively. If equal quantities of alloys are melted to form a third alloy Z then what is the ratio of zinc and aluminium in alloy Z?