Question

(13) At room temperature, He gas in a container can be considered as ideal gas. Its mean translation energy: -; and mean rotation energy : < εR > Its total mea n energy < ε > (b) 1/2 kT (a) 3/2 kT (c) 5/2 kT (d) kT (14) Two of the following molecules have permanent electric dipole moment. They are and (a) CH4 (b) O3 (c) CH3Cl (d) CCl4 Proteins are polymers of amino acids, with structural features of peptide links and α-helices or β-sheets. The peptide links are the proteins; and a-helices or ß-sheets are the (15) structures of structures of proteins (a) secondary (c) quaternary (b) primary (d) tertiary

Answer 1

He is a mono atomic gas For monoatomic substances only translation degree of freedom are present for mono atomic the translation energy = 3/2 times KT Therefore Rotation Energy = 0 Therefore Total mean energy = 3/2 KT + 0 = 3/2 KT 14) Out of CH_4, O_3, CH_2Cl & CCl_4 both O_3 & CH_3Cl have permanent dipole moment. The dipole moment of CH_4 & CCl_4 = 0 Because the symmetrical polyatomic molecules have zero dipole moment the dipole moments of various bands present in the molecule cancel out each others Therefore O_2 & CH_3Cl are not symmetrical 15) The peptide links are the primary structures of proteins It is the linear sequence of aminoacids in a peptide alpha-helices or beta-sheets are the secondary structures of proteins These are held together by hydrogen bonds \r\n 7) For linear molecules, the normal modes of vibration = 3N - 5 N = no of elements