Question

In the Mendeleev table, the triad of the VIII group is:
(A) Ru, Rh, Pd
(B) Cu, Ag, Au
(C) N, O, F
(D) Tl, Pb, Bi

Answer 1

To solve this question, we first need to know how elements are arranged in the Mendeleev periodic table. According to the observation of the Russian chemist Mendeleev, he stated a periodic law according to which "the properties of elements are the periodic functions of their atomic masses."

Complete answer:
Now, in the Mendeleev Periodic table, the elements were arranged in groups and columns in the increasing order of their atomic masses.
Horizontal rows or columns were called periods.
Vertical rows were called groups and the elements found in a group were found to have similar characteristics.
The eight groups were indicated as I, II, III, IV, V, VI, VII, and VIII.
Groups I through VII were further divided into subgroups A and B. The elements of these subgroups had similar properties.
A separate group 0 contained the noble gases.
Group VIII contains 9 transition elements, and is further arranged into three triads based on similarities in their physical and chemical properties.
These triads are
- Iron, Cobalt, and Nickel
- Ruthenium, Rhodium, and Palladium
- Osmium. Iridium, and Platinum

So, in the Mendeleev table, the triad of the VIII group is option (A) Ru, Rh, Pd.

Note:
It should be noted that even though at the time of proposal of Mendeleev's periodic table, it was one of the most systematically arranged tables of elements, it had various drawbacks like confusion about the position of some elements like hydrogen and isotopes, etc.