Question

Which of the following devices is used to measure optical activity?
(A)- Manometer
(B)- Barometer
(C)- Polarimeter
(D)- Hygrometer

Answer 1

Hint: For measuring Optical activity we have to use that type of device which gives us the value of the degree of angle to which the plane polarized light gets rotated from the parent value.

Complete Solution
Optical activity shown by the compounds which are present only in the aqueous state and in those compounds, molecules should have chiral carbon in it. Chiral carbon is that carbon in which all 4 valencies of carbon are fulfilled by 4 different groups.
-Species which fulfill the above condition will show optical activity.
-Optical activity of any compound is measured by the polarimeter.
-Through polarimeter monochromatic (having single wavelength) light will fall to the solution that is prepared from the optical active compounds, which rotates the plane polarized light to clockwise or anticlockwise direction & value of the rotated angle will be observed by the polarimeter.
So, the correct answer is “Option C”.

Additional information: Through polarimeters we can distinguish between the compounds which give optical activity or not.
-In polarimeter sodium lamp is used as a source of light & with this 2 nicol prisms is also present.

Note: In this question some of you may get confused between the option of manometer & polarimeter because manometer is also used for the substances which are present in liquid state, but manometer is used to measure pressure.