Question

Which of the following compounds would be a white, crystalline solid?
A.$C_{3}H_{8}$
B.$CO$
C.$CuCl_{2}$
D.$Cr_{2}O_{3}$
E.$MgO$

Answer 1

Hint: Crystalline solids are the materials with the definite arrangements of its constituent’s i.e. atoms, molecules in its 3-D arrangement. Crystalline solids on being cut with the sharp tool, divide into two pieces having quite a smooth surface and with the definite arrangement they possess the high boiling and the melting point.
Complete step by step answer:
A) $C_{3}H_{8}$: It is an organic compound named propane which belongs to the category alkanes. It is found in gaseous state at room temperature.
B) $CO$: It is a poisonous gas which when inhaled leads to the death of an individual. It binds with an oxygen binding site in blood and creates a deficiency of oxygen in blood.
C) $CuCl_{2}$: It is a chemical compound with light brown solid nature as its physical appearance is known as cupric chloride.
D) $Cr_{2}O_{3}$: It is a chemical compound known as chromium oxide, having major applications to be used as pigment.
E) $MgO:$ It is an ionic compound as the major source of magnesium in nature having the $Mg^{+} $ ions and $O^-$ ions, found in nature as white solid.
Thus option E is the correct option.

Additional information:
MgO Shows stability at the chemical and the physical level even at high temperature which makes it quite suitable to be used as the refractory material.

Note:
Since magnesium oxide is the ionic compound it involves the transfer of electrons between two elements oxygen and magnesium. It prevails in nature as the white crystalline solid having ordered arrangement of its constituents.