Area × speed gives the volumetric flow rate (volume per unit time) of a fluid through a pipe.

Planck's constant has units of energy × time (joule-second), so option C is correct.

The classical fundamental base quantities for mechanics in SI are mass, length and time.

By definition, 1 gray equals 1 joule of energy absorbed per kilogram of mass (1 J kg^-1).

Volumetric strain ≈ ε_longitudinal + 2ε_lateral = ε(1 - 2ν); with ν=0.5 this gives zero volumetric change, i.e., 0%.

Equating pressures gives mercury displacement x = h/(2×13.6) = 27.2/(27.2) = 1 cm, so the level difference is 1 cm.

Support from surface tension is 2TL; equating to weight (mg = 980 dyne for 1 g) gives L = weight/(2T) = 980/(2×70) = 7 cm.

For unit vectors i, j, k, the cross product i × j = k, dot product i · j = 0, and j · j = 1, so all statements are true.

1 poise = 0.1 Pa·s = 0.1 N·s·m^-2, so option B is correct.

Permeability can be expressed in equivalent units (H/m, T·m/A, Wb/(A·m)), so all listed units are valid.