Question

You have three minerals. Mineral A is soft, has cubic cleavage, and breaks easily. Mineral B is soft, has planar breakage and peels into sheets. Mineral C is hard, has rectangular cleavage, and is difficult to break. Which one(s) is/are likely the product of polar covalently bonded molecules?

a) Mineral A ^ Mineral B
b) Mineral C
c) Mineral A
d) Mineral B

Answer 1

Mineral B is most likely the product of polar covalently bonded molecules, as it is soft and has planar cleavage, peeling into sheets like mica. Minerals A and C show characteristics of ionic and covalent network bonding, respectively, rather than polar covalent bonding. The correct answer is D.

Step-by-step explanation:

The minerals described in the question are likely to be products of different types of chemical bonding. The properties of mineral B hint at it being the product of polar covalently bonded molecules. These minerals, such as muscovite (a form of mica), have planar cleavage and tend to peel into sheets due to the layers of covalently bonded atoms within the crystal being held together by weaker van der Waals forces. This is similar to the structure seen in graphite, which also peels into sheets and is soft due to the same type of bonding.

On the other hand, mineral C's hardness and difficulty to break suggest a different type of bonding, likely covalent network bonding, which is present in minerals such as quartz, where atoms are bonded in a continuous network. Mineral A's cubic cleavage and ease of breaking suggest ionic bonding, which is common in minerals such as halite (rock salt) where atoms form a cubic structure and cleave along planes where ionic bonds are weaker. The correct answer is D.