Column AColumn B1C−4 is highly unstable becauseAIt would be difficult for carbon with six protons in its nucleus to hold on just two electrons.2C+4 is achieved byBGaining 4 electrons to its outermost orbit3C+4 is highly unstable becauseCLoosing 4 valence electrons4C−4 is achieved byDIt is difficult for the nucleus with six protons to hold on ten electrons, i.e. four extra electrons

Column AColumn B1C−4 is highly unstable becauseAIt would be difficul

1.	Column AColumn B1C−4 is highly unstable becauseAIt would be difficult for carbon with six protons in its nucleus to hold on just two electrons.2C+4 is achieved byBGaining 4 electrons to its outermost orbit3C+4 is highly unstable becauseCLoosing 4 valence electrons4C−4 is achieved byDIt is difficult for the nucleus with six protons to hold on ten electrons, i.e. four extra electrons
Answer» $\begin{matrix} C o l u m n A & C o l u m n B 1 & C^{- 4} i s h i g h l y u n s t a b l e b e c a u s e & A & I t w o u l d b e d i f f i c u l t f o r c a r b o n w i t h s i x p r o t o n s i n i t s n u c l e u s t o h o l d o n j u s t t w o e l e c t r o n s . 2 & C^{+ 4} i s a c h i e v e d b y & B & G a i n i n g 4 e l e c t r o n s t o i t s o u t e r m o s t o r b i t 3 & C^{+ 4} i s h i g h l y u n s t a b l e b e c a u s e & C & L o o s i n g 4 v a l e n c e e l e c t r o n s 4 & C^{- 4} i s a c h i e v e d b y & D & I t i s d i f f i c u l t f o r t h e n u c l e u s w i t h s i x p r o t o n s t o h o l d o n t e n e l e c t r o n s, i . e . f o u r e x t r a e l e c t r o n s \end{matrix}$