Silicon Silicates Silicones Zeolites - UNSOLVED PRACTICE SET
Chapter: p-Block Elements Groups 13 and 14 | Topic: Silicon Silicates Silicones Zeolites
SILICON SILICATES SILICONES ZEOLITES - UNSOLVED PRACTICE SET
Topic: Silicon Silicates Silicones Zeolites
Multiple Choice Questions
Q1. Silicon belongs to the same group as carbon but differs from carbon because:
- It is a metal
- It cannot form pπ-pπ bonds due to larger size
- It has a lower melting point
- It is not abundant in nature
Q2. Silicones are:
- Silicon-oxygen polymers with organic groups attached
- Pure silicon crystals
- Silicon-carbon compounds with ionic bonds
- Silicon oxides with metal ions
Q3. Zeolites are:
- Naturally occurring silicates with an open three-dimensional structure
- Synthetic polymers of silicon
- Pure silicon dioxide crystals
- Silicon carbide ceramics
Q4. The basic structural unit of silicates is:
- SiO₂
- SiO₄⁴⁻ tetrahedron
- Si₂O₇⁶⁻
- SiO₃²⁻
Q5. Silicones are water-repellent because:
- They contain ionic bonds
- They have organic groups (–CH₃, –C₆H₅) attached to silicon
- They are highly polar
- They decompose in water
Q6. Which type of silicate is formed when two SiO₄⁴⁻ tetrahedra share one oxygen atom?
- Orthosilicate
- Pyrosilicate
- Chain silicate
- Sheet silicate
Short Answer Questions
Q7. Why does silicon not form double bonds (Si=Si) like carbon forms C=C? What does this tell us about the stability of pπ-pπ bonds in silicon?
Q8. Describe the structure of SiO₂ (quartz). Why does it have a very high melting point compared to CO₂?
Q9. What are silicones? Write the general formula of silicones and mention two properties that make them useful.
Q10. Classify the following silicates as ortho, pyro, chain, sheet, or three-dimensional silicates:
(a) Zircon (ZrSiO₄)
(b) Asbestos
(c) Talc
(d) Feldspar
Q11. Your mother uses silicone sealant to fix a leaking pipe in the kitchen. Why is silicone preferred over rubber or plastic sealants for this purpose?
Q12. Why are zeolites called "molecular sieves"? Explain their use as ion exchangers in water softening.
Long Answer Questions
Q13. Discuss the different types of silicates based on the sharing of oxygen atoms between SiO₄⁴⁻ tetrahedra. For each type, give:
(a) The general formula
(b) One example with its chemical formula
(c) A diagrammatic representation of the structure
Cover orthosilicates, pyrosilicates, chain silicates, sheet silicates, and three-dimensional silicates.
Q14. Describe the preparation, properties, and uses of silicones. Include:
(a) How silicones are prepared from alkyl or aryl chlorosilanes
(b) Why silicones are chemically inert, water-repellent, and thermally stable
(c) Uses of silicones as lubricants, sealants, medical implants, and in cosmetics
(d) The difference between silicone oils, silicone rubbers, and silicone resins
Q15. Silicon-based materials are transforming Indian industries. Discuss:
(a) Why India is investing in semiconductor (chip) manufacturing and the role of ultra-pure silicon
(b) The use of zeolites in Indian detergent industries as water softeners and in petroleum refining
(c) How silicone-based products are replacing traditional materials in Indian construction and healthcare
(d) The environmental impact of silicon mining and one sustainable alternative being explored
Numerical / Application-Based Problems
Q16. In the preparation of silicones, dimethyldichlorosilane (CH₃)₂SiCl₂ is hydrolysed and then polymerised.
(a) Write the hydrolysis reaction of (CH₃)₂SiCl₂.
(b) Write the polymerisation reaction showing the formation of a linear silicone polymer.
(c) If 258 g of (CH₃)₂SiCl₂ is completely hydrolysed, calculate the mass of the silicone polymer [(CH₃)₂SiO]ₙ formed. (Assume n = 1 for calculation)
[Given: Atomic masses: C = 12, H = 1, Si = 28, O = 16, Cl = 35.5]
Q17. A zeolite has the formula Na₆Al₆Si₆O₂₄·xH₂O (simplified). In a water softening application:
(a) Write the ion exchange reaction when hard water containing Ca²⁺ ions passes through this zeolite.
(b) If 1 kg of zeolite can exchange 0.15 moles of Ca²⁺ ions, calculate the mass of Ca²⁺ removed.
(c) Calculate the volume of hard water (containing 200 ppm Ca²⁺) that can be softened by 1 kg of this zeolite.
[Given: Atomic masses: Ca = 40, Na = 23, Al = 27, Si = 28, O = 16]
Q18. India's semiconductor mission aims to produce 1 million chips per day. Each chip requires 0.1 g of ultra-pure silicon.
(a) Calculate the daily silicon requirement for this production target.
(b) If silicon is obtained from silica (SiO₂) with 90% efficiency, calculate the mass of SiO₂ needed daily.
(c) If silica sand costs ₹ 2 per kg, calculate the daily raw material cost for silicon production.
[Given: Atomic masses: Si = 28, O = 16]