First Conditional

• 
• Use the first conditional for realistic situations that could happen in the future. The first conditional describes possible results or consequences that can easily come true. 

  
  

  If + present simple, will + base verb*
  

  -If it rains, I will take an umbrella. 

• If there is a fire, we will evacuate the building.	You will need an emergency supply kit if there is an emergency.
  If there is a tornado, we will hear the sirens.	We will go to the second floor if there is a flood.

•  *Another form for first conditional sentences is: will + base verb + if + present simple

Source : Alison