Question

Perovskite is a mineral that has calcium, oxygen and titanium. The unit cell of it's crystalline structure is shown below

The formula of Perovskite and the oxidation number of titanium are respectively:

• A. $CaTi{O}_2,+2$
• B. $CaTi{O}_3,+2$
• C. $CaTi{O}_3,+4$
• D. $CaTi{O}_6,+4$

Answer 1

The correct option is C $CaTi{O}_3,+4$

From the diagram given,
Calcium atoms per unit cell $=8\times \frac{1}{8}=1$
Oxygen atoms are present in the face centers.
Oxygen atoms per unit cell $=6\times \frac{1}{2}=3$
Titanium atoms are present in the body center,
Titanium atoms per unit cell = 1
Thus formula of perovskite is $CaTi{O}_3$
Let, the oxidation number of Titanium be x.
Then, $2+x+3\times (-2)=0$
$\Rightarrow x=+4$