int gas = 0;
int pinAlarma = 8;

void setup() {
  // put your setup code here, to run once:
pinMode(A0,INPUT);
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  gas = analogRead(A0);
  Serial.print("GLP: ");
  Serial.print(gas);
  Serial.println(" ppm");
  if (gas > 100) {
    tone(pinAlarma, 1000, 500); // play tone 60 (C5 = 523 Hz)
  } else {
    noTone(pinAlarma);
  }
  delay(500); // Delay a little bit to improve simulation performance

}