p block

Question 1

p block incudes groups —- to —–

Answer 1

13 to 18

Question 2

p block elements are also called

Answer 2

representative elements

Question 3

____ family is known as the most heterogeneous family and why (4 sentenceS)

Answer 3

boron

1. no regular trend in properties
2. comes after d block
3. lanthanoid contraction
4. poor shelding of d orbitals

Question 4

anamolous behaviour of boron ( 5 points )

Answer 4

1. small size
2. high IE
3. high electronegativity
4. absence of vacant d orbital, so max covalency is 4
5. due to 1 vacant orbital, it is a lewis acid

Question 5

differ in 1 sentence between transition and lanthanoid contraction

Answer 5

transition is cause of poor sheilding of d orbital electron, so size decreses, and lanthanoid is due to f orbital

Question 6

max oxidation state of grp 13 is

Answer 6

3… as max oxidation state is equal to no of valence electrons

Question 7

why stabilty of +3 oxidation state decreases down grp 13

Answer 7

inert pair effect ( like, Tl has [Xe] 4f14 5d10 6s2 6p1, so due to poor sheilding of f and d electrons, there is a lot of effective nuclear charge on s electrons, due to which they dont wanna react, so oxidation state is 1 cause only p electrons will react)

Question 8

why boron has max melting point cause

Answer 8

it exist as B12

Question 9

which element og grp 13 is used to make heat resistent thermometers

Answer 9

gallium, case alltho melting point is less(303K), boiling point is 2676 K

Question 10

what is the trend of melting point in grp 13

Answer 10

decreses frm B to Ga and incresens from Ga to In

Question 11

trend of atomic size in grp 13 with reason

Answer 11

B

Question 12

trend of ionization enthalpy in grp 13 with reason

Answer 12

B>Tl>Ga>Al>In ( due to LN contraction, and poor shielding effect of f electrons, Tl has a lot of nuclear charge, so harder to let go of electon, same way for Ga ie transition contraction)

Question 13

general formula of oxides of grp 13

Answer 13

E2O3

Question 14

general formula of nitrides of grp 13

Answer 14

EN

Question 15

nature of baroium oxide

Answer 15

acidic

Question 16

nature of al, ga oxide

Answer 16

amphoteric

Question 17

nature of In and Tl oxides

Answer 17

basic

Question 18

boron does not react with acid or alkali however it does react with____

Answer 18

conc HNO3 AND concH2SO4

Question 19

Al+HCl—–?

Answer 19

AlCl3 + H2

Question 20

Al+NaOH—-?

Answer 20

NaAlO2+ H2 (sodium aluminate and h)

Question 21

Al+NaOH+H2O—-?

Answer 21

Na[Al(OH)4] + H2

Question 22

Al when reacts with conc. HNO3 , it forms?

Answer 22

passive oxide film

(google:Passive film refers to the spontaneous formation of an ultra-thin film of corrosion product on a metal’s surface that acts as a barrier to additional chemical reaction. aka an inert film)

Question 23

relation between back bonding and acidic strength

Answer 23

inversly

Question 24

the compounds of boron act as lewis acid cause?

Answer 24

presence of vacant orbital

Question 25

borax formulae(there are 2 ways to write)?

Answer 25

Na2B4O7. 10 H2O

Na2 [B4O5 (OH)4].8 H2O

Question 26

preparation of borax formula

Answer 26

H3BO3+ Na2CO3—- Na2B4O7 + CO2 + H2O

Question 27

borax bead test

Answer 27

Na2Br4O7 .10H2O —-(in presence of Pt wire loop) —– Na2Br4O7 + 10H2O —– (heat)——NaBO2+ B203(borax bead or glassy bead)

Question 28

NaBO2 name

Answer 28

sodium metaborate

Question 29

CuO + glassy bead(NaBO2 + B2O3)

Answer 29

Cu(BO2)2+ NaBO2 (blue in color bead)

Question 30

CoO+ glassybead

Answer 30

Co(BO2)2+ NaBO2 (blue in color bead)

Question 31

TiO+ glassy bead

Answer 31

Ti(BO2)2+ NaBO2 (yellow in color bead)