Pure Compound in the Given Options:

The pure compound in the given options can be identified based on its chemical formula and the presence of other elements or compounds in the formula. Here are the options given and their chemical formulas:

a) Sodium fluoride - NaF
b) Sodium silico fluoride - Na2SiF6
c) Hydrofluosilicic acid - H2SiF6
d) Sodium fluro carbonate - Na2CO3F

Out of these options, only Sodium fluoride (NaF) is the pure compound as it contains only Sodium and Fluoride ions and does not have any other elements or compounds. The other options contain Silico, Carbonate, or Acid ions along with Fluoride ions, which makes them impure compounds.

Importance of Identifying Pure Compound:

Identifying pure compounds is essential in various engineering fields, including civil engineering, as the properties and behavior of pure compounds are different from impure compounds. For example, pure compounds have a well-defined melting and boiling point, density, and other physical and chemical properties. They also have a uniform composition and are free from impurities, which makes them more stable and predictable in various applications.

On the other hand, impure compounds can have variable properties and behavior, depending on the type and amount of impurities present. They can also react differently with other substances and may cause undesirable effects, such as corrosion, contamination, or degradation.

Therefore, in civil engineering, it is crucial to use pure compounds in construction materials, such as cement, concrete, and aggregates, to ensure their quality, durability, and safety. Moreover, identifying and analyzing impurities in materials is also necessary to prevent potential damage or failure of the structures.