Answer:
(I) it has 7neutrons
this is because the 13 is the mass number which is the atomic number plus the number of neutron .since the atomic number is 6 and the neutrons are7 the sum is 13
(Ii) protons and neutrons make up the nucleus
(iii) neutrons help make up the nucleus and have no charge/they're neutral
(iv) electrons move in definite paths around the nucleus.these paths are known as energy levels
(v) neutrons.this is because the atomic number is equal to the atomic number plus neutrons
(vi) the density of each element
(vii) 197 this is because the mass number is the sum of protons and neutrons
(viii)a period
(ix) thermal energy and electrical energy
(x) poor conductors of electricity
(xi) alkali metals
(xii)
(xiii)
(xiv)
(xv) it is in group 6-selenium
(xvi) it is in group 8-xenon