Periodic Table, Periodic Properties and Variations of Properties — Chemistry STD 10 — Question

With reference to the variation of properties in the Periodic table, which of the following is generally true?

Among the elements given below, the element with the least electronegativity is :

Ammonia gas turns colourless Nessler's reagent to :

Thick rods of which compounds are used as anode in the fused electrolyte in electrolytic reductions of Alumina?

Assertion (A): Noble gases are unreactive, while atoms of other elements are chemically reactive.
Reason (R): Atoms of other elements complete their octet by losing or gaining electrons.

The reaction taking place at anode during silver plating is:

Nitrate radical is tested by 'brown ring test'. The brown ring is :

When monochloroethane is hydrolysed it forms: