A chemical compound always has the same elements in the same proportions by mass regardless of the source of the compound. This is a statement of A. the law of multiple proportions. B. the law of isotopes. C. the law of definite proportions. D. the law of conservation of mass.

You're actually looking for the de Broglie wavelength here, which, ... the product between its mass and its velocity, as shown by the equation ... kg103g =9.1⋅10−31.kgv=7.0⋅103km s−1⋅103.m1km =7.0⋅106. ... electrons to kilograms and the velocity to meters per second because ... 1 J=1 kg m2s−2.

Explanation: