identifying an argument

Question

Any unit of length, when cubed, becomes a unit of volume. Thus, the cubic meter, cubic centimeter, and cubic millimeter are all units of volume.

- is it valid, invalid, strong, weak or not an argument

Answer 1

Technically, there's a missing second premise, namely: "The meter, centimeter, and millimeter are all units of length." But arguments are rightly considered valid even with "missing" premises like this IF the missing premises are completely obvious and uncontroversial.

If the conclusion had said, "Thus, the cubic meter, cubic volt, and cubic rattlesnake...." then you'd need to add in the appropriate second premise - and would end up with an argument that was valid but unsound because of a false second premise.