Which of the following statements about IR spectrophotometry is false? (2 points)
a. The mid-IR region is the most useful region for qualitative analysis and extends from about 400-2000 
cm^-1 or about 50-2.5 μm
b. All homonuclear diatomic molecules and atoms are invisible in FTIR
c. Vibrational modes such as ν_s and ν_as involve changes in bond length while modes such as τ, ω, ρ and σ
involve changes in bond angle
d. An IR active molecule must have a net change in dipole moment due to vibration or rotation of the 
molecule.
e. The ν_s mode of CO2 accounts for its IR activity.