Analyse the following case and answer the following questions:
A teacher places two objects on the table:
Object A: A silver spoon kept for many days and now covered with a black layer.
Object B: An ice cube kept in a bowl that slowly changes into water.
Object A: A silver spoon kept for many days and now covered with a black layer.
Object B: An ice cube kept in a bowl that slowly changes into water.
1. Which object shows a chemical change?
2. Which object shows a physical change?
3. In which object is a new substance formed?
4. Why is melting ice not a chemical change?