For EM waves (a) (γ) rays have higher penetrating power than x rays...

Here's why: (a) y rays have higher penetrating power than X-rays: True, Y-rays generally have higher energy and thus greater penetrating power. (b) X-rays have higher penetrating power than Y rays: False, Y -rays are more penetrating. (c) Infrared has higher wavelength than X-rays: True, infrared radiation has a much longer wavelength compared to X-rays. (d) Range of visible light is $4000 Å$ to $7000 Å$ : True, the visible light spectrum ranges from approximately $4000 Å$ (violet) to $7000 Å$ (red).