(a) Which two criteria did Mendeleev use to classify the elements in his periodic table?(b) State Mendeleev's periodic law.(c) Why could no fixed position be given to hydrogen in Mendeleev's periodic table?(d) How and why does the atomic size vary as you go: (i) from left to right along a period? (ii) down a group?

(a) Which two criteria did Mendeleev use to classify the elements in h

1.	(a) Which two criteria did Mendeleev use to classify the elements in his periodic table?(b) State Mendeleev's periodic law.(c) Why could no fixed position be given to hydrogen in Mendeleev's periodic table?(d) How and why does the atomic size vary as you go: (i) from left to right along a period? (ii) down a group?
Answer» (a) Which two criteria did Mendeleev use to classify the elements in his periodic table? (b) State Mendeleev's periodic law. (c) Why could no fixed position be given to hydrogen in Mendeleev's periodic table? (d) How and why does the atomic size vary as you go: (i) from left to right along a period? (ii) down a group?