MCQ Detailed View

Viscosity is a measure of a fluid’s resistance to flow. It describes how easily a liquid or gas can move and is influenced by the strength of intermolecular forces, temperature, and pressure. For example, honey has a high viscosity compared to water because it flows more slowly due to stronger internal resistance.

The instrument used to measure viscosity is called a viscometer. There are different types of viscometers, each based on a different principle. The most common types include:

1. 
   

   Capillary viscometer: Measures the time a liquid takes to flow through a thin capillary tube under gravity. Ostwald viscometer is a well-known example.

   
   


2. 
   

   Rotational viscometer: Measures the torque required to rotate an object in the fluid at a known speed. Brookfield viscometer is widely used in industries.

   
   


3. 
   

   Falling sphere viscometer: Determines viscosity by observing the time it takes for a sphere to fall through a liquid under gravity.

   
   

Viscometers are used in many fields, including chemical industries, food processing, pharmaceuticals, petroleum engineering, and material science. For example, viscosity measurement is important in lubricants, paints, and polymer solutions where flow properties affect performance.

Looking at the other options:

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  Hygrometer measures humidity of air, not viscosity.

  
  


• 
  

  Hydrometer measures specific gravity (relative density) of liquids.

  
  


• 
  

  Anemometer measures wind speed and air flow.

  
  

Thus, none of these instruments are suitable for viscosity measurement. Only the viscometer is designed for this purpose.

In physical chemistry, viscosity is a fundamental property used to study fluid dynamics and molecular interactions. Measuring viscosity helps chemists and engineers understand how temperature, pressure, and composition affect fluid flow.

Therefore, the correct instrument for measuring viscosity is the Viscometer.