Expression for the Balmer series to find the wavelength of the spectral line is as follows:
1 / λ = R

Where, λ is wavelength, R is Rydberg constant, and n is integral value (4 here → Fourth level)
Substitute 1.097 x 10⁷ m⁻¹ for R and 4 for n in the above equation
1 / λ = (1.097 x 10⁷ m⁻¹)
= 0.20568 x 10⁷ m⁻¹
λ = 4.86 x 10⁻⁷ m
since 1 m = 10⁹ nm
λ = 486 nm
<h3><u>Answer</u>;</h3>
pH = 4.38
<h3><u>Explanation;</u></h3>
Consider that ;
[H3O+] = 10-pH mol/L
Therefore; the pH is the -log of the [hydronium ion].
pH = - log [H3O+]
Thus;
pH = - log (4.2 × 10^–5)
= 4.38
She will most likely observe that the temperature
does not change during melting because the heat absorbed is used to overcome
intermolecular forces rather than to increase the kinetic energy of the
particles if she measures the temperature of the water in the beaker.
Answer:
3. D
28. also known as Freon 12
Explanation: