Question

Demerits of Mendeleev periodic law
And
Metal+metal , non metal+non metal , metal+ non metal

Answer 1

Answer:

Demerits of mendeleev's periodic table was

He could not place hydrogen at it's proper position.

There was no regular trend of increasing atomic mass on moving across table.

Isotopes of elements were found which violated mendeleev's periodic table.

Answer 2

Answer:

Demerits of Mendeleev periodic law

,were

1. (a) Mendeleev arranged elements in the ascending order of their atomic masses. There was no fixed position for hydrogen in his periodic table, as it resembled alkali metals as well as halogens.
2. (b) Elements of higher atomic mass were placed before elements of lower atomic mass. Cobalt with atomic mass 58.93 was placed before nickel with atomic mass 58.71.
3. (c) Elements having different properties were placed in the same sub group like manganese (Mn) was placed with halogens which had totally different properties

ques 2

Metal+metal,metal+ non metal -----> Ionic bond

non metal+non metal ,non metal+metalloid ----->covalent bond