Which of the following characteristics are because of physical changes?  

1. No new substances are formed.  
2. Products are identical to the reactants.  
3. These changes are reversible.  
4. Properties of products are different from the properties of reactants.  
5. Most of the chemical changes are irreversible.  
6. These changes always result in energy changes.  

Characteristics of Physical changes:  

• No new substances are formed.  
• Products are identical to the reactants.  
• These changes are reversible.  

Characteristics of Chemical changes:  

• Properties of products are different from the properties of reactants.  
• Most of the chemical changes are irreversible.  
• These changes always result in energy changes.