1 atomic mass unit is defined as approximately 1.6606 × 10^-27 kg, corresponding to option A.

Area ∝ diameter^2 so halving diameter reduces area by 4, causing extension to increase by factor 4: 1 cm × 4 = 4 cm.

Barometer height h = P/(ρg), so with same P and g on the moon ≈ g/6, the column height is ≈6× that on Earth, i.e., 6 × 760 mm.

Stoke's law gives the viscous drag force on a sphere moving slowly through a viscous fluid.

A fathom is a traditional unit used to measure the depth of water.

Heating the water locally changes surface tension and creates flows that typically pull the floating sticks together, so they come closer.

Same volume gives L_A/L_B = 4 and area ratio A_A/A_B = 1/4, so extension ratio = (L/A) ratio = 4 × 4 = 16.

The SI base unit for thermodynamic temperature is the kelvin.

One bar equals 100,000 pascals, i.e., 1 × 10^5 N/m^2.

The SI unit for solid angle is the steradian.