Red light has a wavelength of 70 A°. In “nm” it is A. 7 nm B. 0.07 nm C. 70 nm D. 700 nm

The correct answer is C. 70 nm.

1 angstrom (Å) is equal to 0.1 nanometers (nm). Therefore, 70 Å is equal to 70 x 0.1 = 7 nm.

The other options are incorrect.

Option A: 7 nm is too small. The wavelength of visible light is typically in the range of 400 to 700 nm.

Option B: 0.07 nm is too small. The wavelength of X-rays is typically in the range of 0.01 to 10 nm.

Option D: 700 nm is too large. The wavelength of infrared light is typically in the range of 700 to 1000 nm.