Question

Pycnometer method is used for the determination of which of the following properties of grains?

• A. Surface roughness
• B. Bulk density
• C. Specific gravity
• D. Colour

Hint:

Pycnometer $\rightarrow$ Specific gravity True density.
Standard measuring container/hopper $\rightarrow$ Bulk density.
Spectrophotometer/Colorimeter $\rightarrow$ Colour.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
A pycnometer is a precision laboratory glass flask of accurately known volume used to determine the true density and specific gravity of liquids, solids, and granular materials via fluid/gas displacement.
Key Formula or Approach:
\[ \text{Specific Gravity } (\text{SG}) = \frac{\rho_{\text{grain}}}{\rho_{\text{water}}} = \frac{m_{\text{grain}}}{m_{\text{displaced fluid}}} \times \text{SG}_{\text{fluid}} \]

Step 2: Detailed Explanation:
In post-harvest and seed physical property analysis:
1. Bulk density: Measured directly using a standard volume cup and scale (mass per unit gross volume including inter-granular voids).
2. True density and Specific gravity: Determined using an air comparison pycnometer or liquid pycnometer (toluene or alcohol displacement) by measuring the true volume occupied by grain particles excluding void spaces.

Step 3: Final Answer:
Thus, the pycnometer method is used to determine Specific gravity, corresponding to option (C).