P-block Elements (grp 13 & 14)

Question 1

Electronegativity order for group 13 elements is

Answer 1

B >Tl >In > Ga > Al

Pnemonic: botingal

Question 2

Atomic radii order for group 13 elements

Answer 2

B

Question 3

Ionization energy order for group 13 elements is

Answer 3

B > Tl >Ga >Al >In

*Botigain

Question 4

Standard reduction potential for group 13 elements is

Answer 4

Tl >In >Ga >B >Al

*Thaingabali

Question 5

What’s inert pair effect?

Answer 5

Reluctance of participation of ns² electrons due to poor shielding of f-electrons.

Question 6

Hydroxides of B,Al,Ga,In,Tl are soluble/insoluble except H3BO3 or B(OH)3.

Answer 6

Insoluble.

Question 7

All (B,Al,Ga,In,Tl) form tri-halides except TLI3.

Answer 7

TLI3 is unstable so it’ll not exist.

TLI is stable and exists.

Question 8

Trihalides behave as Lewis acids(electron deficient). What’s the order of Lewis acid character for group 13 elements?

Answer 8

BX3 >AlX3 >GaX3 >InX3

Thallium doesn’t form trihalide.

Question 9

AlCl3 is _______but in aqueous state it becomes ________.

a) covalent , ionic
b) ionic, covalent
c) covalent, covalent
d) ionic, ionic

Answer 9

AlCl3 is covalent but in aqueous state it becomes ionic.

Question 10

All trihalides are sp² hybridised & covalently bonded except flourides of __,__,__,__.

Answer 10

Al, Ga, In, Tl

Question 11

Lewis acid character for group 13 elements is

Answer 11

BX3 > AlX3 > GaX3 > InX3

Question 12

All trihalides undergo hydrolysis except ____.

Answer 12

BF3.

Question 13

Formula & lewis dot structure of borax.

Answer 13

Na2B4O7.10H2O or Na2[B4O5(OH)4].8H2O

Module SP-5 pg.no.87

Question 14

Which of these is true for borax:

1) BO4 units =2
2) BO3 units =2
3) sp ³ hybridised B = 2
4) sp ² hybridised B = 2
5) B-O-B bonds = 5
6) B-O bonds = 14
7) bridged O = 5

Answer 14

All are correct.

Question 15

N-factor of borax is

Answer 15

2

Question 16

Borax bead test is for

Answer 16

Transition metals ions.

Question 17

Chemical composition of glassy bead is

Answer 17

NaBO2 + B2O3
# B2O3 is reactive component of glassy bead.

Question 18

Whats the colour if bead when glassy bead reacts with CuO?

Answer 18

Blue bead.
= copper metaborate
= Cu(BO2)2

Question 19

Whats the colour if bead when glassy bead reacts with CoO?

Answer 19

Deep blue.
= Co(BO2)
= cobalt metaborate.

Question 20

Whats the colour if bead when glassy bead reacts with TiO?

Answer 20

Yellow bead.
= titanium metaborate
= Ti(BO2)2

Question 21

Whats the colour if bead when glassy bead reacts with NiO?

Answer 21

Reddish brown
=Nickel metaborate
=Ni(BO2)2

Question 22

Boric acid is a weak monobasic lewis acid.

T/F

Answer 22

True.

Question 23

Hybridisation of boric acid changes from __ to __ on reacting with water.

Answer 23

sp² to sp³

Question 24

H3BO4 on heating at 100° C gives

Answer 24

Metaboric acid i.e HBO2 and H2O

Question 25

Metaboric acid on heating at 160 ° C gives

Answer 25

Tetraboric acid i.e H2B4O7 and H2O

Question 26

Tetraboric acid on red hot heat gives

Answer 26

Boron trioxide i.e B2O3 and H2O.

Question 27

Diborane is electron deficient eventhough its a dimer.

T/F

Answer 27

True.

Question 28

Which type of bond is found in B2H6.2NH3

a) covalent
b) ionic
c) co-ordinate
d) all three i.e covalent, ionic,co-ordinate

Answer 28

All three.. i.e covalent,ionic,co-ordinate bonds are present in diborane-diamonia complex i.e B2H6.2NH3

Question 29

Formula for borazine is

Answer 29

B3N3H6.

aka inorganic benzene or borazole or borazine.

Question 30

Borazine is

a) aromatic
b) sp² hybridised
c) isoelectronic with benzene but more reactive
d) all- a) b) c)
e) only a & b

Answer 30

d) all a) b) c) are correct