Silicon is the second most abundant element (~27.2%)in the earth's after oxygen (45.5 %) Carbon. Silicon, germanium, tin and lead constitute the group 14 of the periodic table. Chemistry of silicon is distinctly different from that of carbon. For example, under standard conditions CO_(2) is a gas whereas SiO_(2) is a covalent solid. The reason for the distinct difference in the properties of CO_(2) and SiO_(2) is : (a)carbon is more electronegative then O and in case of SiO_(2) oxygen is more electronegative than silicon (b)carbon has a small size and forms a pi bond with good overlap whereas silicon has larger size hence has a poor pi overlap ( c)carbon has only 'rho' orbitals and lacks 'd' orbitals whereas silicon has 'd' orbitals (d)first ionization potential of carbon is higher than that of silicon (1086 kJ mol^(-1) for C and 786 kJ mol^(-1) for Si).

Silicon is the second most abundant element (~27.2%)in the earth's aft

1.	Silicon is the second most abundant element (~27.2%)in the earth's after oxygen (45.5 %) Carbon. Silicon, germanium, tin and lead constitute the group 14 of the periodic table. Chemistry of silicon is distinctly different from that of carbon. For example, under standard conditions CO_(2) is a gas whereas SiO_(2) is a covalent solid. The reason for the distinct difference in the properties of CO_(2) and SiO_(2) is : (a)carbon is more electronegative then O and in case of SiO_(2) oxygen is more electronegative than silicon (b)carbon has a small size and forms a pi bond with good overlap whereas silicon has larger size hence has a poor pi overlap ( c)carbon has only 'rho' orbitals and lacks 'd' orbitals whereas silicon has 'd' orbitals (d)first ionization potential of carbon is higher than that of silicon (1086 kJ mol^(-1) for C and 786 kJ mol^(-1) for Si).
Answer» ANSWER :A::B::C::D