As we know that wavelength and frequency is inversely proportional to each other. Greater the wavelength smaller the frequency and vice versa.
Solution:
The relation between wavelength and frequency is as follow,
υ = c / λ
where
υ = frequency = ?
c = velocity of light = 3.0 × 10⁸ ms⁻¹
λ = wavenumber = 542 nm = 542 × 10⁻⁹ m
Putting the given values,
υ = 3.0 × 10⁸ ms⁻¹ / 542 × 10⁻⁹ m
Result:
υ = 5.53 × 10¹⁴ s⁻¹
Answer:

Explanation:
When percentage composition is given, and asked for the empirical formula, it is simplest to assume 100 g of material. Thus,
Mass C = 40.92 g. Moles C = 40.92 g x 1 mole/12 g = 3.41 moles C
Mass H = 4.58 g. Moles H = 4.58 g x 1 mole/1.0 g = 4.58 moles H
Mass O = 54.50 g. Moles O = 54.50 g x 1 mole/16 g = 3.41 moles O
Now, we want to get the moles into whole numbers, so we begin by dividing all by the smallest, i.e. divide all values by 3.41.
Moles C = 3.41/3.41 = 1
Moles H = 4.58/3.41 = 1.34
Moles O = 3.41/3.41 = 1
Now, in order to get 1.34 to be a whole number we multiply it (and all others) by 3
Moles C = 1x3 = 3
Moles H = 1.34x3 = 4
Moles O = 1x3 = 3
Empirical Formula 
Energy=mass x the speed of light squared.
Answer:
XL(toluene) = 0.77
XL(benzene) = 0.23
Explanation: see attachment
Answer:
recordando también que ** 1mL = 1cm ^ 3 **
(como ** 1 dm ^ 3 = 1 L **)