Electromagnetic spectrum regions defined by wavelength ranges

Steps:

• Convert wavelength: 1.0 × 10^{-7} m = 100 nm.
• Recall standard ranges: ultraviolet (10–400 nm), visible (400–700 nm), infrared (700 nm–1 mm), X-ray (0.01–10 nm).
• Compare: 100 nm falls between 10 nm and 400 nm.
• Classify: Matches ultraviolet region.

Why B is correct:

• Ultraviolet radiation spans 10–400 nm per standard electromagnetic spectrum definitions, and 100 nm fits exactly within this interval.

Why the others are wrong:

• A. Infrared starts at wavelengths longer than 700 nm.
• C. Visible light ranges from 400–700 nm only.
• D. X-rays have wavelengths shorter than 10 nm.

Final answer: B