The answer is pH. A nonaqueous solution has no water in it, so there's nothing to measure a pH against.
Volume, shape, and mass all still apply to a nonaqueous liquid the same as any other — those aren't off the table. pH is different: it's specifically a measure of hydrogen-ion concentration in water, so anything water-free, like an alcohol- or oil-based product, simply falls outside what the pH scale can describe.
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