What is the range of LM35 temperature sensor? Can i use to record temperature of a room?
The LM35 when correctly connected can be used to sense any temperature in the range of -55 to 150°C.
However when connected directly to the Bolt WiFi module, you can only monitor a temperature in the range of 0 to 100 °C
This is because the Bolt WiFi module has an analog input pin with an input range of 0 to 1v, which corresponds to a temperature range output of 0 to 100°C for the LM35 sensor.
I am asking about the area in which it can sense the temperature? I want to record the temperauture of a room of area 6400 square feet.
The area of detection of the sensor is its immediate vicinity, and depends highly on the environment.
The temperature will certainly not be the same for the whole of your 6400 sq feet area, and as such it will be impossible to use a single temperature sensor to detect the temperature of the whole area (Regardless of what temperature sensor it is).
In such cases, the best thing to do, is to place a sensor in the region of extreme temperature. For example near a window, or a heater or a cooler.
This will give you the bound of the temperature within your area, and that is the best that can be done.