Embibe Experts Solutions for Chapter: Classification of Elements and Periodicity in Properties, Exercise 1: EXERCISE-1

Which of the following match is correct:

True statement is:

The screening effect of $\mathrm{s}$ orbital electron is:

In the first $100$ elements, number of $\mathrm{s}$-block elements are:

In a period, the elements having least melting point are:

The covalent and vander waal's radii of hydrogen respectively are:

the electronic configuration of two neutral elements $\mathrm{A}$ and $\mathrm{B}$ are $\mathrm{A}=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$ and  $\mathrm{B}=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^5$

Which element do not have valency equals to its group no. :