Provide reason for each of the following:
(i) Discarding the law of triad.
(ii) Sodium is kept in kerosene oil.
(iii) Concentrated sulphuric acid is not used to dry hydrogen
(iv) when water is stored in sealed bottle for long time, etchings are observed at surface of container.
(v) Some elements exhibits variable valency
Answers
Answer:
too long question it becomes social science answer
I) According to the law of triads when three elements having same properties were arranged in ascending order of the atomic masses , the average of the first and third elements' atomic masses is the atomic mass of the second element.
The law of triads was rejected because Doberiener failed to arrange all the known elements in form of triads.
Besides,The law did not fully apply within the same family.
II) Sodium is a very reactive metal . It is kept in kerosene to prevent it from coming in contact with moisture and oxygen to form Sodium hydroxide.
III) Concentrated sulphuric acid is not used to dry hydrogen because it is a strong oxidising agent and will oxidise hydrogen to water .
IV) Etchings are left on the surface because water absorbs small amount of fibre from the vessel.
V) Some elements show variable valency because of the different electronic configurations. They can sometimes lose more electrons than are present in its valence shell i.e. loss from the penultimate shell and show variable valecy.