A kinematic chain is known as a mechanism when: | Agrigyan

In-situ field unit weight / density of soil is determined using Core-cutter method (C), Sand replacement method (D), and Water replacement method (E) (used for coarse gravelly soils). Pycnometer (A) determines specific gravity/water content in lab, and Oven dry method (B) determines moisture content. Option analysis: (A) Includes lab water content/SG methods. (B) Oven dry determines water content, not unit weight. (C) (C), (D) and (E) only are the standard field unit weight determination methods. (D) Includes pycnometer.

Statement (I) is true: fine-grained clays possess flocs and microscopic pore structures yielding void ratios often exceeding $0.8$ to $\gt 2.0$, whereas coarse sand/gravel has dense packing with void ratio typically $0.3$ to $0.7$. Statement (II) is false: when soil is fully saturated, the degree of saturation $S = 1$ ($100\%$); the void ratio $e = V_v/V_s$ can be any positive value, independent of saturation. Option analysis: (A) Statement (II) is false. (B) Statement (I) is true. (C) Statement (I) is true but Statement (II) is false is the correct answer. (D) Inverted.

By Jurin's law, capillary rise height is inversely proportional to pore radius ($h_c = \frac{4\sigma \cos \theta}{\gamma_w d}$). Clay soils have extremely small microscopic pore channels ($d \ll 0.002\text{ mm}$), resulting in theoretical capillary rise of several meters, whereas sandy soil has large macropores resulting in capillary rise of only a few centimeters to tens of centimeters. Option analysis: (A) Capillary rise is greater in clay than sand due to smaller pore diameter. (B) Contradicts Jurin's law. (C) Pores are vastly different sizes. (D) Capillary rise occurs in both.