You should be able to (a)   all the properties of metals and non-metals.

A selectively permeable (a)   in the nervous system allows $$Na^+$$  and $$K^+$$  ions to pass through.

Elements (a)   their valence electrons when forming covalent bonds.

Chlorine (Cl) atom (a)   one electron to form chloride ( $$Cl^-$$  ) ion.

The picture shows a velocity-time graph with (a)   velocity (zero acceleration).

My biology teacher draws a (a)   to show the process of respiration in a cell.

Nitrogen oxide, water and nitrogen dioxide are some examples of covalent (a)