neet centre 2021

Dobereiner arranged elements as 1. groups 2. periods 3. triads 4. All the above

Triads means 1. Small groups of Three elements 2. Small groups of Four elements 3. Small groups of Five elements 4. Small groups of Six elements

The first classification of elements is attempted by 1. Dobereiner 2. Mendeleff 3. Mosley 4. John A.R. Newlands

According Mendeleef periodic law the proper ties of elements are the periodic functions of their …… 1. Atomic numbers 2. Atomic weights 3. Atomic sizes 4. Atomic volumes