Can anyone help me with this

Determine the expected diffraction angle for the first-order reflection from the (310) set of planes for bcc chromium when monochromatic radiation of wavelength 0.0735 nm is used. the atomic radius for cr is 0.1249 nm.

Assuming weightless pulleys and 100% efficiency, what is the minimum input force required to lift a 120 n weight using a single fixed pulley?

Ain is , is 's of ? 0.62 0.79 1.27 1.50