Question

Mendeleev’s periodic law is based on:-
A. Atomic Weight
B. Atomic Number
C. Number of neutrons
D. None of the above

Answer 1

Hint: In order to the question, we should go through the Mendeleev’s Periodic Table and check on what basis Mendeleev arranged his periodic table and then we’ll definitely reach towards the conclusion

Complete answer:
Mendeleev’s periodic law is based on Atomic Weight. When we state Mendeleev’s periodic law, the properties of elements are a periodic function of their atomic masses. It was the discovery of atomic number which led to a change in Mendeleev's periodic law which was based on atomic mass.The atomic weight of an element may sometimes be amended by a knowledge of those of its contiguous elements. Subsequently the atomic weight of tellurium should lie somewhere in the range of 123 and 126, and can't be 128. (Tellurium's nuclear weight is 127.6, and Mendeleev was inaccurate in his presumption that nuclear weight should increment with position inside a period.)
According to Mendeleev, the properties of elements are a periodic function of their atomic weights. Mendeleev left the gap under aluminium and a gap under silicon, and called these elements Eka-Aluminium and Eka-Silicon.
Hence, the correct option is ‘(A) Atomic Weight’.

Note: Drawback of Mendeleev’s Periodic table:-
$ * $ Elements with large differences in properties were included in the same group. For example, hard metals like copper and silver were included along with soft metals like sodium and potassium.
$ * $ The increasing order of atomic mass was not strictly followed throughout. For example in cobalt and nickel & Tellurium and Indium.