Question

the first element in newlands table is ( ) a) Cs b) Mg c) Ba d) H​

Answer 1

Answer:

Q1. Did DobereinerA's triads also exist in the colurrxrts of Ne lord's Octaves? Compare and find out.

Ans. Yes, it exists in the Iewland's octave. It is Li, Na and

Q2. What were the limitations of Dobereiner's classification?

(a) All the existing elements were not classified.

(b) D bereiner could identify only three triads from the elements.

Hence this system wa4s not useful.

Q3. What were the limitations of Newlands� Law of Octaves?

Ans. • Newlands’ law was applicable only till calcium, after Ca, every eighth element did not possess properties similar to first.

• New elements discovered did not fit into the law.

• Wrong order of arrangement of elements was done, e.g. Co and Ni do not resemble halogen were found together in same slot, Fe being similar to Co and Ni was separated and kept in different slot.

Q4. Use Mendeleev's Periodic Table to predict the formulae for the oxides of the following elements:

K, C, Al, 1Si, Ba