Answer: Helium (He) and Selenium (Se) both are non metals ends with ium sound
Explanation:
He is a inert gas and Se belongs to oxygen family (VI A group)
A is the answer
In an ozone molecule, the three atoms must be connected, so there must at least be a single bond between them. Place
dots in pairs around the oxygen atoms until each oxygen atom has eight valence electrons, starting with the atoms on the
outside and doing the central atom last if there are enough. Do not exceed the total number of valence electrons
identified in part A. Remember that the dashes between the oxygen atoms, which represent single bonds, each indicate
the presence of two valence electrons
J. J. Thomson discovered electron by performing an experiment using cathode ray tubes. High voltage across is applied across two electrodes at that causes a beam of particles to flow from the the negatively-charged electrode that is cathode to the positively-charged electrode that is anode. Properties of the particles, are tested using two oppositely-charged electric plates around the cathode ray. The cathode ray was deflected away from the negatively-charged electric plate and towards the positively-charged plate. This indicated that the cathode ray was composed of negatively-charged particles. And these negatively charged particles are called electrons.
