question_answer

                For a cubic crystal structure which one of the following relations indicating the cell characteristic is correct?

A)                                                                                                                                                                                             \[a\ne b\ne c\] and \[\alpha \ne \beta \] and \[\gamma \ne {{90}^{o}}\]            

B)                  \[a\ne b\ne c\] and \[\alpha =\beta =\gamma ={{90}^{o}}\]

C)                  \[a=b=c\] and \[\alpha \ne \beta \ne \gamma ={{90}^{o}}\]      

D)                  \[a=b=c\] and \[\alpha =\beta =\gamma ={{90}^{o}}\]

Correct Answer: D

Solution :

                In cubic crystals, the crystal axes are perpendicular to one another \[(\alpha =\beta =\gamma ={{90}^{o}})\] and the repetitive interval is the same along the three axes \[(a=b=c)\].                                 Note:    Cubic crystal may be simple, body centred or face centred.