Wavelength And Frequency

A particle is subjected to a potential described as follows:

Here, and . If the energy of the particle , which one of the following schematics is a valid quantum mechanical wavefunction ( ) for the system?

The X-ray diffraction pattern of a monatomic cubic crystal with rigid spherical atoms of radius 1.56 Å shows several Bragg reflections of which the reflection appearing at the lowest 2𝜃 value is from (111) plane. If the wavelength of X-ray used is 0.78 Å, the Bragg angle (in 2𝜃, rounded off to one decimal place) corresponding to this reflection and the crystal structure, respectively, are