Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3 to n = 2) as 660 nm, the wavelength of the 2nd Balmer line (n = 4 to n = 2) will be:

Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3

1.	Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3 to n = 2) as 660 nm, the wavelength of the 2nd Balmer line (n = 4 to n = 2) will be:
A.	889.2 nm
B.	488.9 nm
C.	642.7 nm
D.	388.9 nm
Answer» C. 642.7 nm