PRACTICE QUESTIONS SET

How many shells are present in the elements of the second period?

Write the number of vertical columns in the modern periodic table. What are these columns called?

An element 'X' has mass number $35$  and number of neutrons $18$. Write atomic number and electronic configuration of 'X'. Also write group number, period number and valency of 'X'

Two elements 'P' and 'Q' belong to the same period of the modern periodic table and are in Group-$1$ and Group-$2$ respectively. Compare their following characteristics in tabular form :
(a) The number of electrons in their atoms   
(b) The sizes of their atoms
(c) Their metallic characters 
(d) Their tendencies to lose electrons
(e) The formula of their oxides 
(J) The formula of their chlorides. 
 

From the following elements :  ${}_4\mathrm{Be}$, ${}_9\mathrm{F}$, ${}_{19}\mathrm{K}$ and ${}_{20}\mathrm{Ca}$   
Select
(a) the element having one electron in the outermost shell.
(b) two elements of the same group.
Write the formula of and mention the nature of the compound formed by the union of ${}_{19}\mathrm{K}$ and element X $(2,8,7)$.
 

Differentiate between the arrangement of elements in Mendeleev's periodic table and Modern periodic table.

A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming.

(a) Identify A, B and C.
(b) To which group of periodic tables does A belong?

Mention one property each of the elements in a group and of elements in a period in the modern periodic table.