grade 11 p block

Question 1

Borazine formation

Answer 1

B2H6 + NH3 —-> B3N3H6 + H2

Question 2

B2H6 prep from LiAlH4 and NaBH4

Answer 2

LiAlH4 + BF3 ——–> B2H6 + LiF + AlF3

NaBH4 + I2 —–> B2H6 + NaI + H2

Question 3

Prep of boric acid from borax

Answer 3

Na2B4O7 + HCl + H2O ———–> H3BO3 + NaCl
or
Na2B4O7 + H2O ——> NaOH + H3BO3

Question 4

Prep of boric anhydride

Answer 4

B2H6 + O2 ——> B2O3 + H2O

Question 5

Heating of borax

Answer 5

Na2B4O7 ————–> B2O3 + NaBO2

Question 6

Fullerene structure

Answer 6

Smooth structure with no dangling bonds
Aromatic
Even no of carbon atoms

Question 7

H3BO3 on heating

Answer 7

H3BO2, then B2O3

Question 8

Silicate structure

Answer 8

SiO4 4-

Only single bonds between Si and O

Question 9

Zeolite charge

Answer 9

-ve

Question 10

ZSM 5 use

Answer 10

Alcohols directly converted to gasoline

Question 11

Grp 13 element having high MP

Answer 11

B

Question 12

Shape of dimer of AlCl3

Answer 12

tetrahedral

Question 13

TlI3

Answer 13

does not exist

Question 14

Borax bead test for Co

Answer 14

Co(BO2)2 is formed which is blue in color

Question 15

H3BO3 solubility in water

Answer 15

Sparingly soluble in normal water, highly soluble in hot water

Question 16

Flux for soldering metals

Answer 16

Borax

Question 17

Cu vs Al conductivity

Answer 17

On a weight to weight basis, Al has twice the conductivity of Cu

Question 18

Electronegativity of grp14

Answer 18

C > Si = Ge = Sn = Pb

Question 19

Grp 13 BP

Answer 19

B > Al > Ga > In > Tl

Question 20

SiCl4 + H2O

Answer 20

Si(OH)4

silicilic acid

Question 21

Oxides nature of grp14

Answer 21

CO2: acidic
Si: acidic
Ge: acidic
Sn, Pb: Amphoteric

Question 22

SiO can exist only at

Answer 22

high temp