Question

On the basis of Mendeleev’s Periodic Table given below, answer the questions that follow the table:
(a) Name the element which is in
(i) Ist group and 3rd period.
(ii) VIIth group and 2nd period.
(b) Suggest the formula for the following:
(i) oxide of nitrogen
(ii) hydride of oxygen
(c) In group VIII of the Periodic Table, why does cobalt with atomic mass 58.93 appear before nickel having atomic mass 58.71?
(d) Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his Periodic Table?
(e) Using atomic masses of Li, Na and K, find the average atomic mass of Li anf K and compare it wit the atomic mass of Na. State the conclusion drawn from this activity.
(

Answer 1

Answer:

.1st group and third period-na

.2nd group and 7th period-ta

.oxide of nitrogen-Oxides of nitrogen are a mixture of gases that are composed of nitrogen and oxygen. Two of the most toxicologically significant compounds are nitric oxide (NO) and nitrogen dioxide (NO2). Other gases belonging to this group are nitrogen monoxide (or nitrous oxide, N2O), and nitrogen pentoxide (NO5).