P-block XII (grp 15,16..) Flashcards

1
Q

N2 is ______ while others are

A

N2 is diatomic others are polyatomic.

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2
Q

All except ____ show allotropy. (In grp 15)

A

N

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3
Q

N cant form d π - p π bond ??

A

Bcz of absence of d-orbital

But can show p π - p π bond

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4
Q

Common oxidation state of grp 15 is

A

+3,-3,+5

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5
Q

Tendency to show -3 oxidation state ______ down the grp due to??

A

Decreases.

Due to increase in size and metallic character.

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6
Q

____ hardly forms any cmpd in -3 oxi. State?

A

Bi

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7
Q

Stability of ____ oxi. State increases while of ____ decreases down the group.(grp 15)

A

+3 increases , +5 decreases

Due to inert pair effect.

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8
Q

Characteristic compound of Bi in +5 oxi. State is??

A

BiF5

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9
Q

3HNO2 —->

A

HNO3 +H2O +2NO

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10
Q

All elements of group 15 form hydrides of the form EH3.

T/F

A

T

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11
Q

Thermal stability, basicity,bond dissociation enthalpy, bond angle of hydrides of grp 15 _____ down the grp.

A

Decrease.

Reducing charac. Increases down the grp.

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12
Q

Boiling point order for hydrides of grp 15 is

A

PH3

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13
Q

Melting point order of grp 15 hydrides is

A

PH3

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14
Q

Boiling point order of grp 15

A

N <p></p>

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15
Q

Melting point order of grp 15 elements

A

N <p></p>

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16
Q

Chile saltpeter is

17
Q

Indian saltpeter is

18
Q

+3 oxi. State of __,__,__ become stable with respect to disproportionation. (Grp 15)

A

As, Bi, Sb

19
Q

Oxide in higher oxi. State are more stable than in lower oxi. State.
(T/F)

20
Q

Designate acidic, amphoteric, basic to oxides of grp 15 of the form E2O3.

A

N2O3 and P2O3 = purely acidic
As2O3 and Sb2O3 = amphoteric
Bi2O3 = predominately basic

21
Q

Give nature of N2O, NO, NO2

A

N2O & NO = neutral oxides

NO2 = mixed anhydride

22
Q

All trihalides except of ___ are unstable. (Grp 15)

A

N
Only NF3 is known to be stable.
Except BiF3 other trihalides are predominantly covalent.

23
Q

Except ___ all trihalides of grp 15 are predominantly covalent.

24
Q

Preparation of dinitrogen

A

In laboratory,
NH4Cl + NaNO3 —> N2 + 2H2O + NaCl

Thermal decomposition of sodium/barium azide (for very pure N2),
Ba(N3)2 ——> Ba + 3N2
2NaN3 —-> 2Na + 3N2

{N3^-1 is k/a azide.}

25
6Li + N2 —-> | 3Mg + N2 —->
2Li3N | Mg3N2
26
At high temperature, | N2 + O2 —-> 2NO
True
27
Preparation of ammonia
On small scale, NH4Cl + Ca(OH)2 —->2NH3 + 2H2O + CaCl2 On large scale, by Haber’s process, N2 + 3H2 ——>NH3 ΔH = -46.1 Kj/mol (exothermic)
28
Optimum conditions for formation of ammonia are?
High pressure | Temperature ≈ 700K
29
Cu^2+ (blue) + 4NH3 ——> | AgCl (white ppt.) + 2NH3 ——>
Cu^2+ (blue) + 4NH3 ——> [Cu(NH3)4]^2+ (deep blue) | AgCl (white ppt.) + 2NH3 ——> [Ag(NH3)2]Cl (colourless)
30
NH3 is highly soluble in water. Precipitates hydroxides of many metals from their salts. Forms ammonium salt with acids. Is a lewis base. Which one of these is true?
All are true.
31
Preparation of nitric acid?
In laboratory, NaNO3 + H2SO4 ——> NaHSO4 + HNO3 On large scale by Ostwald’s process, 3 step process.
32
Ostwald’s process ??
1) 4NH3 + 5O2 ——> 4NO + 6H2O. (In presence of Pt/Rh gauge catalyst) 2) 2NO + O2 ——>2NO2 3) 3NO2 + H2O ——> HNO3 + NO