Element X consist of two isotopes with masses of 62.9 and 64.9. The relative atomic mass of the element is 63.6. What is th e percentage abundance of the lighter isotope? Show your working out.

How does the principle of electromagnetism explain the interaction between earth’s magnetic field and the solar wind?

Acrystal that absorvd water from air is (blank)a. aqueousb. homogenousc. hygroscopicd. efflorescent

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?