The molecule in which all the carbon atoms are $$s{p^2}{\text{ - hybridised}}$$ will be coplanar. Thus, in option (A)
i.e.
all carbons are $$s{p^2}{\text{ - hybridised}}{\text{.}}$$
287.
The structure of isobutyl group in an organic compound is
$$'Iso’$$ mean’s one $$Me$$ group is present in side chain. Hence, the structure of $$iso-butyl$$ group in an organic compound is
( $$'yl’$$ suffix is used to represent one $$-H$$ less than the parent hydrocarbon. )
288.
Due to the presence of an unpaired electron, free radicals are :
NOTE : Dipole moment is a vector quantity.
Methane molecule being symmetrical, has zero dipole moment. Replacement of one of the $$H - $$ atoms by $$Cl$$ atom increases the dipole moment. The increase in dipole moment is rather more than what can be expected because of the fact that the bond dipole moment of $$C - H$$ bond and that of $$C - Cl$$ bond reinforce one another. Replacement of another $$H$$ atom by $$Cl$$ increases the bond angle due to lone pair - lone pair repulsion
between two $$Cl - $$ atoms thereby reducing the dipole moment of the molecule. Increase in angle is again caused by the the introduction of the third $$Cl - $$ atom. When the fourth $$Cl - $$ atom is introduced, the molecule $$\left( {CC{l_4}} \right)$$ again becomes symmetrical and dipole moment reduces to zero. So, $$C{H_3}Cl$$ will have the maximum dipole moment.