Hello I am new to Arduino
and I have a Arduino Uno and MQ4,MQ5,MQ7
and I am trying to read the reading from this three sensors at once is it possible ?
if it is how do I approach it?
I want to take the reading of all the three sensors and display it on the monitor and possibly turn on buzzers/LED for each of the sensor
First, learn to take readings from each sensor and display the results.
What you want to do is possible if "at once" really means within a few milliseconds of each other.
Connect the three sensors to three different analog inputs and read those inputs sequentially. You won't notice the lag!
Inaccurate readings can occur when switching between different analog inputs, so it helps to read each input twice in a row, and just ignore the first reading.
And to make it even easier, the very very first example shows you how to read an analog input and display the result.
Then have a look at if() to see how to compare that reading to some threshold and turn your buzzer or led on or not.
Maybe try to take an average of say 5 samples per pin. It will only take a micro second but accuracy will be better.
look at this: averaging an analog sensor value - Programming Questions - Arduino Forum