The number of electrons, protons and neutrons in a species are equal to 18, 16 and 16 respectively. Assign the proper symbol to the species. 

Symbols  can be written, whereas symbols  are not acceptable. Answer Briefly.

Atomic number is defined in terms of protons and not in terms of electrons. Why?

What type of waves does light constitute?

Who proposed solar model of atom?

Give the range of wavelengths of visible light.

27. Mark one pair each of isobars and isotones from the following:
             

Calculate the number of neutrons in dipositive zinc ion (Zn²⁺, the mass number being 70).

What is the charge on 1 mole of neutron?

Calculate the number of electrons which together weigh one gram.