The two liquids which are often used in thermometer on experiment basic is known as

Analysis of the Question

This question tests your knowledge of thermometric substances. It asks you to identify the two liquids commonly used in liquid-in-glass thermometers for scientific experiments and general temperature measurement.

Concept Explanation

A thermometric substance is a material that undergoes a measurable, regular physical change when its temperature changes. For a liquid to be suitable for a thermometer, it must:

1. Expand uniformly with temperature.
2. Have a high boiling point and a low freezing point to cover a wide range of temperatures.
3. Be easily visible (often colored).
4. Not stick to the walls of the glass capillary tube.

Mercury and Alcohol are the two most common liquids used because they meet these criteria effectively.

• Mercury is excellent for high temperatures because it has a high boiling point ($357^\circ\text{C}$) and does not wet glass.
• Alcohol (usually colored ethanol) is excellent for low temperatures because it has a very low freezing point ($-115^\circ\text{C}$), making it ideal for measuring cold environments where mercury would freeze.

Step-by-Step Solution

1. Evaluate Option A: Mercury is used, but it is not the only liquid used in thermometers.
2. Evaluate Option B: Water is never used in thermometers because it is transparent, has a small range of expansion, and wets glass, which makes it inaccurate.
3. Evaluate Option C: Mercury and Alcohol are the two standard liquids used in laboratory and clinical thermometers. This aligns with the physical properties required for accurate temperature measurement.
4. Evaluate Option D: Alcohol is used, but mercury is also a standard liquid, so this is incomplete.

Conclusion

Based on the principles of thermal physics, Mercury and Alcohol are the two primary liquids used in thermometers.

Exam Tip: Remember the "Mercury vs. Alcohol" rule: Mercury is for high temperatures (it's a metal, so it's robust), and Alcohol is for low temperatures (it stays liquid even in freezing conditions).