Question

In a monoclinic unit cell, the relation of sides and angles are, respectively :

• A. $a=b\ne c$ and $\alpha =\beta =\gamma ={90}^o$
• B. $a\ne b\ne c$ and $\alpha =\beta =\gamma ={90}^o$
• C. $a\ne b\ne c$ and $\beta =\gamma ={90}^o\ne \alpha$
• D. $a\ne b\ne c$ and $\alpha \ne \beta \ne \gamma \ne {90}^o$

Answer 1

Answer: (C)

$a\ne b\ne c$ and $\beta =\gamma ={90}^o\ne \alpha$

monoclinic crystal is one of the 7 crystal system. In monoclinic system, the crystal is describe by vectors of unequal lengths,

So, we have $a\ne b\ne c$ and $\beta =\gamma ={90}^0\ne \alpha$

Option C is correct.