1. Q1.Boron is unable to make BF63- ion. Explain.
Solution : Due to non-availability of d-orbitals, boron is unable to expand its octet.
Therefore the maximum covalency of boron cannot exceed 4
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Gogin Haridas XI A

2. Q2.White fumes appear around the bottle of anhydrous aluminium chloride. Give reasons
Solution: Anhydrous aluminium chloride is partially hydrolysed with atmospheric moisture to liberate HCl gas. Moist HCl appears in white colour.
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Gogin Haridas XI A

3. Q3.Why is boric acid considered as weak acid?
Solution: Because it is not able to release H+ ions on its own. It receives OH- ions from water molecule to complete its octet and in turn releases H+ ions .
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Gogin Haridas XI A

4. Q4. Standard electrode potential values for Al3+/Al is -1
Q4. Standard electrode potential values for Al3+/Al is V and that of Tl3+/Tl is+1.26 V. Predict about the formation of M3+ ions in solution and compare the electropositive character of the two metals.
Solution: Standard electrode potential values for two half cell reactions suggest that aluminium has the highest tendency to make Al3+ ions, whereas Tl3+ is not only unstable in solution but is powerful oxidising agent.
Thus Tl+ is more stable in solution than Tl3+.Aluminium being able to form +3 ions easily, is more electropositive than thallium.
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Gogin Haridas XI A

5. (iii) Silicon and germanium
Q5. Select the members of group 14 that (i) forms the most acidic dioxide ,(ii) is commonly found in +2 oxidation state (iii) used as a semi-conductor.
Solution: (i) Carbon
(ii) Lead
(iii) Silicon and germanium
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Gogin Haridas XI A

6. Q6. Diamond is covalent, yet it has high melting point. Why?
Solution: Diamond has a three dimensional network involving C-C bonds, which are very difficult to break and in turn has a melting point.
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Gogin Haridas XI A

7. Q7. [SiF6]2- is known whereas [SiCl6]2-not.Give possible reasons.
Solution: The possible reasons are:
Six large chloride ions cannot be accommodated around Si4+ due to limitation of its size.
Interaction between lone pair of chloride ion and Si4+ is not very strong.
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Gogin Haridas XI A

8. They are hydrophobic (water repellant) in nature
Q8.What are silicones?
Solution: Simple silicones consist of chains in which alkyl or phenyl groups occupy the remaining bonding positions on each silicon.
They are hydrophobic (water repellant) in nature
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Gogin Haridas XI A

9. THANK YOU
9/19/2018
Gogin Haridas XI A