Why are Group first elements called alkali metals?

The Group first elements are called alkali metals because they form water soluble hydroxides. Like LiOH, NaOH, KOH, RbOH and CsOH etc.

Why potassium carbonate cannot be prepared by Solvay process?

Potassium carbonate cannot be prepared by Solvay proces due to the reason that potassium bicarbonate (KHCO3) formed as an intermediate (When CO2 is Passed through ammoniated solution of potassium chloride) is highly soluble in water and can not be separated by filteration.

Which has more torsianal strain, butane or 2-methylbutane?

2-Methylbutane. It has two staggered conformer's with two Methyl group's adjacent to each other and one Methyl at a distance. The third staggered conformer has all three Methyl's adjacent to each other, and has the highest energy. Butane has only two Methyl groups to consider. There are two conformers with adjacent Methyl's, and one lowest energy conformer. the anti form.

Account for the shorter C-O length in an ester compared with an anhydride?

A degree of cross-conjugation exists in the anhydride; this competition for electrons decreases the delocalization to each carbonyl O and gives the C-O sigma bond less double bond character.

Explain the significance of bond order. Can bond order be used for quantities comparisons of the strengths of chemical bonds?

Bond order is defined as half the difference between th electrons present in the bonding and the antibonding orbitals. Integral value of 1, 2, or 3 corresponds to single, double or triple bonds respectively as studied in classical concept. The bond order may be taken as an approximate measure of the bond strength. As the bond order increases bond length decreases and bond strength increases.