Questions

From first figure : each fig has the value of 20 => It has inside 4 figures => Each individual figure has the value of '5'

From second => Each Triangle has the value of '1' (bcoz it contains two in each)

From third => Figure star has the value of '4'

Then in fourth => 4 + 1 + 15 = 20

Hydrogen is the common element in all acids.

Sulphur is an yellow element that stinks when burned.

Intermolecular forces :

The forces of attraction present in between the molecules or atoms or compounds is termed as intermolecular forces.


The molecule HCl is composed of hydrogen and chlorine atom. There is high difference in electronegativities therefore, it is polar in nature. The H end of HCl is permanently slightly positive charge. The Cl end of HCl has a permanent slight negative charge. the "H" in one molecule is attracted to the "Cl" in a neighbor. The intermolecular force is weak compared to a covalent bond. But this dipole-dipole interaction is one of the stronger intermolecular attractions.

It also has hydrogen bonding and dispersion forces. 

Dispersion forces are the weakest forces which are present in between all molecules or atoms.
Hydrogen bonds are present in molecules having at least one H-A bond where A is the strong electronegative atom (mainly F, Cl and N).