int mq=A0,b=7;
float sv;
void setup(){
  Serial.begin(9600);
  Serial.println("WARMIng");
  delay(20000);
}
void loop(){
  sv=analogRead(A0);
  Serial.println(sv);
  if(sv>150)
  tone(b,1000);
  else
  noTone(b);
  delay(1000);
}