Quartz is very hard and melts at 1550∘C . Reason is:a)separate S...
Explanation:
Quartz is a mineral composed of silicon dioxide (SiO2). It is one of the most abundant minerals on Earth and has various industrial uses due to its hardness and high melting point. The reason for its hardness and melting point can be explained by the type of chemical bonds present in quartz.
Covalent Bonds in Quartz:
Quartz (SiO2) primarily consists of silicon-oxygen covalent bonds. Covalent bonds are formed by the sharing of electrons between atoms. In the case of quartz, each silicon atom is covalently bonded to four oxygen atoms, and each oxygen atom is covalently bonded to two silicon atoms. This arrangement forms a three-dimensional network structure of interconnected SiO4 tetrahedra.
Extending Throughout the Sample:
The silicon-oxygen covalent bonds in quartz extend throughout the entire sample. This means that each silicon atom is bonded to nearby oxygen atoms, and these bonds continue in all directions, creating a strong and interconnected network.
Hardness of Quartz:
The presence of covalent bonds in quartz leads to its hardness. Covalent bonds are very strong, and breaking them requires a substantial amount of energy. Therefore, quartz is a hard mineral that can scratch most other common minerals.
Melting Point of Quartz:
The high melting point of quartz can also be attributed to its covalent bonds. Melting involves breaking the bonds between atoms or molecules. In the case of quartz, the strong covalent bonds between silicon and oxygen atoms require a high temperature of 1550°C to break and convert the solid quartz into a liquid state.
Conclusion:
In conclusion, the correct answer is option 'D' - Quartz (SiO2) has silicon-oxygen covalent bonds that extend throughout the sample. The presence of these strong covalent bonds gives quartz its hardness and high melting point, making it a valuable mineral in various industries.
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