2. The development of the ultra microscope makes use of the __________________.
3. The energy of electron is taken as zero when it is ___________________.
[A]In the k-shell
[B]In the orbit
[C]Far from the nucleus
[D]In its ground state
4. The hydrogen ion is ____.
5. The main use of salt in the diet is to __________________________________.
[A]Increase the solubility of food particles in water
[B]Make the taste of food better
[C]Ease the process of cooking
[D]Produce hydrochloric acid in small amounts for the digestion of food