The Modern Periodic Table

Assertion (A) : Sixth period is the longest period in the periodic table.

Reason (R) : Sixth period involves the filling of all the orbitals of the sixth energy level.

Arrange the following in proper order of atomic size

Which of the elements, whose atomic number are given below, cannot be accommodated in the present set up of the long form of the periodic table?

The correct order of filling up of subshells in the seventh period is

All the lanthanoids and actinoids belong to group _____ of the periodic table.($3/4$).

Among the elements from atomic number $1$ to $36$, the number of elements which have an unpaired electron in the $\mathrm{s}$-subshell is $6$.

The first member of lanthanoid series is lanthanum.

All the lanthanoids and actinoids belong to group _____ of the periodic table.($3/4$)

Elements having the similar outer electronic configuration in their atoms are arranged in the same _____.

Define representative elements?

Which of the elements, whose atomic number are given below, cannot be accommodated in the present set up of the long form of the periodic table?

Which of the following groups does helium belongs?

All of the group$-\mathrm{I}$ elements have ${\mathrm{ns}}^1$ valence shell electronic configuration and the properties of an element have

Which of the following statement is incorrect?

$3\mathrm{d}-$transition series of elements start with scandium which has the electronic configuration

Successive filling of $3\mathrm{s}$ and $3\mathrm{p}-$orbitals give rise to the third period. The number of elements present in this period are 

An element $\mathrm{A}$ belongs to third period and fifteenth group of the periodic table. Which one of the following is true regarding the outer electronic configuration of $\mathrm{A}$?

The fifteen elements from Lanthanum to Lutetium are named as _____

An element has its electronic configuration as 2, 8, 2. To which period does this element belong?

An element has its electronic configuration as 2, 8, 2. What is the group of this element?