Question

an atom contains 3 protons electrons and 4 neutrons atomic number mass number and valency

Answer 1

atomic no. is 3. mass no. is 7(neutrons+electrons) and valency is 1

Answer 2

it's atomic no would be 3as protons are 3
it's mass no would be 7 as mass no =no of protons+no of neutrons
by this we can say that the element is lithium and it's valency would be 1 as it's electronic configuration is 2,1