The answer to this problem is quite simple, it’s 9
It is a column of elements in the periodic table of the chemical elements.
Synthetic rubber also has shortcomings, the main drawback exists in its tensile effect is relatively poor, tear strength and mechanical properties are relatively poor
Alpha particles are helium nucleus ! so answer is A !
it is made by ionization of helium, when both the electrons are out , then two unit of positive charge is one helium and thus called alpha particle !
