// you have to make sure that you either have
// sensors with unique I2C addresses
// or you have multiple I2C busses
// or you have some means of isolating individual
// sensors from the bus.
Maybe AWOL´s answer was too short .... but it is perfect
// you have to make sure that you either have
// sensors with unique I2C addresses
// or you have multiple I2C busses
// or you have some means of isolating individual
// sensors from the bus.
I2C chips are usually very small and the address range is limited (2, 4, 8 devices).
If all the chips are the same, you will have a problem.
Multiple I2C busses are a good idea, i have had one one on my Arduino Uno so far.
So do not expect any experience from me.
Isolating chips from the bus means the existence of an Enable/Disable Chip pin.
Maybe you can select/disable 20 chips (4 addresslines chips) witch 5 Arduino pins,
however, this gets complicated.
If it is a graduation project, you should be able to figure this out.
We will help you, but will not do your graduation project.
Why do you not tell us more about your project?
Do you want to measure temperature, pressure or ....
Which sensors are you going to use.
A multiplexer chip might also help you to distinguish between different segments of sensors.
Many I2C sensors also have an address pin that allows the address to be toggled between two values. You can have unlimited sensors on one bus and uniquely toggle the address pin on the sensor you wish to address. For example, the GY-521 sensor has an address of 0x68 with address low and 0x69 with address high. Keep all addresses low and communicate with one sensor using address 0x69 by bringing its address high.