Question

Which one of the following steps is INCORRECT while reading a laboratory thermometer?

• A. Don't hold the thermometer by its bulb.
  
• B. Hold the thermometer in a straight vertical direction, while it is inside the material.
• C. Take the reading of the thermometer after removing it from the material.
• D. Read the thermometer keeping the level of mercury along the line of sight.
  

Answer 1

The correct option is C Take the reading of the thermometer after removing it from the material.

It is advised not to hold the thermometer by its bulb while reading it because if we hold a thermometer by its bulb, the mercury in the bulb will expand due to our body temperature and effect the actual reading.

To obtain the correct reading from a lab thermometer, it should be kept upright (straight vertical direction).When the thermometer is kept tilted, the mercury will not rise to the appropriate level.
This will result in an incorrect reading.

The lab thermometer should not not be removed from the object whose temperature is to be measured. If we do so, the mercury level falls as there is no kink and we cannot get the actual reading.

The correct way to read a thermometer is by keeping the level of mercury along the line of sight. When we read the temperature on a thermometer, it should be vertical and our eyes should be levelled with the top of the liquid in the glass tube.