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1. Equimolar mixture of hydrogen and carbon monoxide – water gas and the mixture of carbon monoxide and nitrogen – producer gas are important industrial fuels 

2. Carbon monoxide is a good reducing agent and can reduce many metal oxides to metals. 

3. Carbon monoxide is an important ligand and forms carbonyl compound with transition metals

(a) Graphite

(b) allotropism

Diamond is very hard.

(b) producer gas

Important ore of boron is borax.

(d) Thallium

1. Grey tin 

2. White tin

3. Rhombic tin 

4. Sigma tin

1. Amorphous boron 

2. a-rhombohedral boron 

3. p-rhombohedral boron 

4. γ – rhombohedral boron 

5. α – tetragonal boron 

6. β – tetragonal boron

(c) Carbon nanotubes

6 allotropes are possible for boron.

(b) Aluminium

(d) B(OCH₃)₃

1. There is intermolecular hydrogen bonding in H₂O molecule but there is no hydrogen bonding in H₂S .

2. The S-H bond is weaker than O-H bond because size of S atom is greater than that of O atom. Hence H₂S can dissociate to give H ions in aqueous solution.

3. In the higher oxidation state, S can combine only with highly electronegative elements like F.

1. Rhombus 

2. Monoclinic

(b) Na[BH(OR)₃] 

1. Certain elements can exist in different forms with different physical property and same chemical properties.

2. b -sulphur is prepared by melting a - sulphur in a dish and cooling, till crust is obtained. Holes are then pierced into the crust, and the liquid is taken out. On removing the crust, needle shaped β -sulphur is obtained.

B₂H₆ is highly reactive compound.

(c) Borazole

(a) A and R are correct and R explains A.

The compound used as a flux in metallurgy is Borax.

(b) A and R are correct and R not explains A.

(a) Metal borides

Borax is basic in nature.

a) White Qhosfhorus It consists of discrete tetrahedral P4 molecules.

b) i) Pyrosuiphuncacid

ii) H₂S₂O₇ + H₂O → 2H₂SO₄

c) Flounne or HOF or hypoflourous acid

d) Compounds – Xe F₂, XeF₄ Xe O₃, Xe OF₂ etc.,

a) Disproportionation reactions are a special type of redox reaction in which an element in one oxidation state is simultaneously oxidised and reduced. In phosphorous acid (H₃PO₃) phosphorus is in the intermediate oxidation state of +3. It is increased to +4 (oxidation) in phosphoric acid (H₃PO₄) and decreased to – 3 (reduction) in phosphine (PH₃).

b) PCI₃ undergoes hydrolysis in presence of moisture giving fumes of HCI. PCI₃ + 3H₂O → H₃PO₃ + 3HCI

c) i) Contact Process

(b) A and R are correct and R not explains A.

This is because of angular strain in the P₄ molecule where the angles are only 60°.

a) i) Nitrogen atom in NH₃ has one lone pair of electrons which is available for donation. There fore, it acts as a Lewis base.

ii) PCI₃ hydrolyses in the presence of moisture giving fumes of HCI. PCI₃ + 3H₂O → H₃PO₃ + 3HCI

iii) Fluorine is the most electronegative element and cannot exhibit any positive oxidation state. Fluorine atom hasno d orbitals in its valence shell and therefore cannot expand its octet.

b) i) Xenon ditluoride, XeF₂

Xenon tetrafluoride, XeF₄

Xenon hexafluonde, XeF₆ (any two)

ii) XeF₂ is prepared by treating Xe with excess fluorine at 673 Kandl bar.Xe(g)+F2( g)⟶673 K,1 bar >XeF2( s)

Or,

XeF₄ is prepared by treating Xe with excess fluorine in 1: 5 ratio at 873 K and 7 bar.

Xe(g)+2 F2( g)⟶B73 K,7bar→XeF4( s)

Or,

XeF₆ is prepared by treating Xe with excess fluorine in 1 :20 ratio at 573 K and 60 – 70 bar.

Xe(g)+3 F2( g)⟶573 K,60−70bar⟶XeF6( s)

OR

a) i) Due to small size and high electronegativity of oxygen it is capable of forming hydrogen bond. Thus, water molecules can associate through intermolecular hydrogen bonds and hence ¡t exists as a liquid.

Due to big large and low electronegativity of sulphur t is not capable of forming hydrogen bond. So hydrogen sulphide molecules cannot associate through intermolecular bonds and hence it exists as a gas.

ii) Noble gases being monoatomic have no interatomic forces except weak dispersion forces and therefore, they are liquefied at very low temperatures. Hence, they have low boiling points.

iii) NO₂ contains odd numberof valence elecrons. It behaves as a typical odd electron molecule. On dimensation, it is converted to stable N₂O₄ molecule with even number of electrons.

b) i) These are compounds formed by the reaction between two different halogens.

ii) dF, BrF, IF, BrCI, ICI, dF₃, BrF₃, IF₃, ICI₃, IF₅,
BrF₅, dF₅, IF₇ 

¹⁰B₅ isotope is used as moderator in nuclear reactors.

(c) Sodium borate

(a) diborane

4. They have low boiling points and are highly volatile

Iodine is formed when potassium iodide reacts with a solution of CuSO₄ .

4. HIO₄ , ICl₅ , I₂ , HI  

4. A is false, but R is true.

2. The greatest difference between the various oxidation states of bromine is 5. 

(b) K₃[AlF₆]

AlF₃ + 3KF → K₃[AlF₆]

Cl₂O₇ one is the anhydride of HClO_4.

CO₂ is regarded as a hydride of carbonic acid because it dissociates in to water and carbon dioxide.

H₂CO₃ → H₂O + CO₂

Zeolites: 

1. Zeolites are three dimensional crystalline solids containing aluminium, silicon and oxygen in their regular three dimensional framework. 

2. They are hydrated sodium alumino silicates with general formula, Na₂O. (Al₂O₃). x(SiO₂)y(H₂O) (x = 2 to 10; y = 2 to 6) 

3. Zeolites have porous structure in which the monovalent sodium ions and water molecules are loosely held. 

4. The Si and Al atoms are tetrahederally coordinated with each other through shared oxygen atoms.

5. Zeolites structure looks like a honeycomb consisting of a network of interconnected tunnels and cages. 

6. Zeolite crystal to act as a molecular sieve. They helps to remove permanent hardness of water

(i) As we move down a group, the atomic size increases and the stability of the hydrides of group 15 elements decreases. Since the stability of hydrides decreases on moving from NH₃ to BiH₃, the reducing character of the hydrides increases on moving from NH₃ to BiH₃

(ii) The two N atoms in N₂ are bonded to each other by very strong triple covalent bonds. The bond dissociation energy of this bond is very high. As a result, N₂ is less reactive at room temperature.

1. It is because BiH₃ is least stable among the hydrides of group 15 elements.

2. Bleaching action of chlorine is due to oxidation. The nacent oxygen ([O]) produced is responsible for the bleaching action.

CI₂ + H₂O → 2HCI + [O]

Coloured substance + [O] → Colourless substance

Zeolites are widely used as a catalyst in petrochemical industries for cracking of hydrocarbons and isomerization.

BiH₃, because the stability of hydrides decreases on moving from SbH₂ to BiH₃.

NH₄Cl(aq) + NaNO₂ (aq) → N₂ (g) + 2H₂O(l) + NaCl(aq)

Alkyl or aryl substituted silicon chlorides, R_nSiCl_(4-n)

(c) sulphonic acid

Sulphuric acid is manufactured by contact process, catalyst used in contact process is V₂ O₅.

Deacon’s process is used to manufacture Cl₂.