" /> -->

#### p - Block Elements - I Important Questions

12th Standard EM

Reg.No. :
•
•
•
•
•
•

Chemistry

Time : 01:00:00 Hrs
Total Marks : 50
5 x 1 = 5
1. In diborane, the number of electrons that accounts for banana bonds is

(a)

six

(b)

two

(c)

four

(d)

three

2. The element that does not show catenation among the following p-block elements is

(a)

Carbon

(b)

silicon

(c)

(d)

germanium

3. The repeating unit in silicone is v

(a)

SiO2

(b)

(c)

(d)

4. The geometry at which carbon atom in diamond are bonded to each other is

(a)

Tetrahedral

(b)

graphene

(c)

Fullerene

(d)

dry ice

5. AlF3 is soluble in HF only in the presence of KF. It is due to the formation of (NEET)

(a)

K3[AIF3H3]

(b)

K3[AiF6]

(c)

AIH3

(d)

K[AIF3H]

6. 5 x 2 = 10
7. Describe briefly allotropism in p- block elements with specific reference to carbon

8. Boron does not react directly with hydrogen. Suggest one method to prepare diborane from BF3.

9. Explain the formation of boron trifluoride.

10. Mention the physical properties of boranes.

11. What are the uses of boron trifluoride?

12. 5 x 3 = 15
13. Complete the following reactions
a.$B(OH)+NH_{ 3 }+NH\longrightarrow$
b.$Na_{ 2 }B_{ 2 }{ O }_{ 7 }+{ { H }_{ 2 }{ SO }_{ 4 }+{ H }_{ 2 }O\longrightarrow }$
c.${ B }_{ 2 }{ H }_{ 6 }+2NaOH+2{ H }_{ 2 }O\longrightarrow$
d.${ B }_{ 2 }{ H }_{ 6 }+{ CH }_{ 3 }OH\longrightarrow$
e.${ BF }_{ 3 }+9{ H }_{ 2 }O\longrightarrow$
f.$HCOOH+{ H }_{ 2 }{ SO }_{ 4 }$
g.$SiCl_{ 4 }+{ C }_{ 2 }{ H }_{ 5 }OH\longrightarrow$
h.$SiCl_{ 4 }+{ NH }_{ 3 }\longrightarrow$
i.$B+NaOH\longrightarrow$
j.${ H }_{ 2 }{ B }_{ 4 }{ O }_{ 7 }\overset { Red\quad hot }{ \rightarrow }$

14. How is aluminum chloride prepared from aluminum?

15. Give 3 uses of aluminium chloride

16. Describe the structure of graphite.

17. How is CO2 manufactured?

18. 4 x 5 = 20
19. How will you convert boric acid to boron nitride?

20. A double salt which contains fourth period alkali metal (A) on heating at 500K gives (B). aqueous solution of (B) gives white precipitate with BaCl2 and gives a red colour compound with alizarin. Identify A and B.

21. How are silicates classified? Give an example for each type of silicate.

22. Distinguish between diamond and graphite.