You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO₃, ZnCl₂ and H₂O. In which of the above containers these solutions can be kept?

The solutions of dilute HCl, ZnCl₂ and H₂O can be kept in the container that is made of Copper. The Aluminium container can hold dilute HNO₃ and H₂O.
We can store a solution in a container with which the solution will not react.
When compared to Aluminium, copper is a less reactive metal. Also, Copper is placed below Hydrogen in the activity series. Therefore, it will not react with dilute HCl or H₂O; due to which we can store them in the copper container. However, dilute HNO₃ being a strong oxidising agent, will react with Copper and hence cannot be stored in a copper container. Copper, being less reactive than Zinc, will not react with ZnCl2.
Aluminium, on the other hand, is highly reactive and can react with the said solutions. However when dilute HNO₃ comes in contact with Aluminium, a protective layer of Aluminium Oxide is formed which prevents further reaction. Therefore, dilute HNO₃ can be stored in an Aluminium container.
Also, Aluminium does not react with water. So, water can be stored in the Aluminium container as well.

Note:
The activity series of metals refers to the list of metals ranked in the decreasing order of their reactivity in order to displace Hydrogen gas from water or acid solutions. It helps us in predicting which metal will displace which metal in Acidic solutions.