

$\underset{A}{\mathop{PhF}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underset{B}{\mathop{PhCl}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underset{C}{\mathop{PhBr}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underset{D}{\mathop{PhI}}\,$


ઉપરની વાતાવરણીય પ્રક્રિયાના તબક્કામાં $A$ અને $B$ શોધો.
