Question

(1) State two main characteristics of elements on which modern
periodic table is based.

(ii) No fixied position can be assigned to hydrogen in the periodic
table why.

(iii) In Mendeleev's periodic Table, why was there no mention
of Noble gases like Helium, Neon & Argon.
5marks​

Answer 1

1) Two main things on which modern periodic table is based are a) atomic number. b) On their properties.

ii) There was no fixed position for Hydrogen as it acts like halogens as well as like alkali metals.

III) As during Mandeleev's time noble gasses where not found. As a result he couldn't place it in his periodic table.

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