1) the elements which are arranged in regions on the basis of energy sub level are called blocks
Example: the family of halogens, family of noble gas
2) Mendeleev's periodic law has been restated to say that when the elements are arranged in order of increasing atomic number, there is a periodic pattern in their chemical and physical properties.: this is true
3) Ramsey discover noble gases
4) technetium is man made element
5) The elements Be , Mg , Ca , Sr Ba, Ra belongs to alkaline earth metals
6) Atomic number is number of protons
7) an atom of oxygen has proton = 8 , neutron = 8 and electron = 8
8) This is not true
generally increases as atomic radius decreases within a group
9) Argon has most number of valence electrons
10) The valence electrons in carbon = 4
so there will be four valence electrons around carbon in lewis structure
11) There are five electrons in valence shell of nitrogen so if it will lose five electron it will achieve duet not octet
12) The sulphur atom has six electrons in outermost shell so it will lose six electron achieve
