Model Question Paper I

Dry ice is basically used as a cooling agent. It is the solid form of carbon dioxide gas. It sublimates at -78.5°C.

Diamond and quartz both are very hard solids and so they have high melting points.

In auto-reduction, no external agent is used as a reducing agent. Here, sulphide ores of less electropositive metals like Hg, Pb, Cu etc. are heated in air so as to convert part of the ore into oxide or sulphate which then reacts with the remaining of sulphide ore in absence of air to give the metal and sulphur dioxide.

Here, Cu itself acts as the reducing agent and also it is being reduced so, this process is termed as auto-reduction.

As dilute sulfuric acid is ideal for redox titration because it is neither an oxidizing agent and nor a reducing agent. On the other hand, KMnO₄ which is the indicator, oxidises HCl to Cl₂ as HCl is a mild reducing agent_. Due to which, the purpose of the experiment is not served. So, dilute sulphuric acid is used.

The main carbon chain has 3 carbon atoms, so it is ‘prop’, and the carbon adjacent to the N atom would be named as 1. Then there is one double bond in the second carbon position (en) and 1 N-methyl amine in the first carbon position.

Therefore IUPAC name is N-methylprop-2-en-1-amine.

The common name for this compound is allylmethylamine.

2-amino-4-pentene has 5 carbon atoms in the main chain.

Conductivity of an electrolyte depends on :-

(i) Nature of electrolyte- The conductance of an electrolyte depends upon the number of ions present in the solution. Therefore, the greater the number of ions in the solution the greater is the conductance. The number of ions produced by an electrolyte depends upon its nature.

(ii) Concentration of electrolyte- The conductance of an electrolyte varies with the concentration of the electrolyte. In general, conductance increases with decrease in concentration or increase in dilution.

A colloid is any substance that is made of particles that are of an extremely small size- larger than atoms but generally have the size of 10^-7 cm ranging to 10^-3 cm. Repulsive forces between charged particles having the same charge prevent them from colliding when they come across each other. As a result of which, presence of equal and similar charges on colloidal particles provide stability to them due to repulsion. This erratic random movement of the particles is also termed as Brownian motion.

A colloid is any substance that is made of particles that are of an extremely small size- larger than atoms but generally have the size of 10^-7 cm ranging to 10^-3 cm. Traces of electrolytes stabilizes the colloids. Dialysis is the separation of colloids from dissolved ions or molecules of small dimensions, or crystalloid, in a solution. Thus, on prolonged dialysis, electrolytes are separated thereby destabilizing the colloids.

Carbon and hydrogen are good reducing agents but they are not used to reduce metallic oxides at high temperatures. This is because, at high temperatures, they can react with the metals itself, thereby forming carbides and hydrides respectively which are not desired.

The presence of linear structure and strong intermolecular hydrogen bonding most importantly leads to close packing of chains due to which we get the crystalline nature of nylon.

Sucralose is a tri-chloro derivative of sucrose is an artificial sweetener. Its appearance and taste are similar to that of sugar but is 600 times sweeter than sugar.

(Image of Sucralose)

(Image of Sucrose)

Gallium is a trivalent element while germanium is tetravalent.

On doping germanium with gallium, some of the crystal sites are occupied by gallium atoms. Three electrons of gallium make bonds with germanium while the 4th electron of germanium remains unbounded and thus is free for movement and increases the conductivity of crystal. This place is deficient of electrons and is called electron hole or electron vacancy. The movement of electrons (or electron holes) results in increase in conductivity of germanium.

When we look at the electronic configurations of Nitrogen, Flourine and chlorine, we see that only chlorine has a vacant d orbital.

N : [He] 2s² 2p³

F : [He] 2s² 2p⁵

Cl : [Ne] 3s² 3p⁵

Ne : [He] 2s² 2p⁶

He :1s²

Due, to the presence of the vacant d orbital, Cl can easily accommodate the electrons during the hydrolysis of NCl₃ which NF₃ cannot do. So, NCl₃ gets hydrolysed easily.

In [Fe(H₂O)₆]³⁺

Electronic configuration of Fe is: [Ar]3d⁶4s²

[Ar] = 1s²2s²2p⁶3s²3p⁶

Electronic configuration of Fe⁺³ = [Ar]3d⁵

Outer electronic configuration of Fe⁺³ = 3d⁵

Oxidation number of Fe is +3

The electrons remain unpaired because H₂O is weak field ligand. Total no. of the unpaired electron, n = 5.

We know,

Spin only magnetic moment is given by:

μ = [n(n + 2)]^1/2

μ = [5×7]^1/2 [As, unpaired electrons are 5]

μ = 5.916BM

Hybridization is sp³d².

In case of [Fe(CN)₆]^3-

Electronic configuration of Fe is: [Ar]3d⁶4s²

[Ar] = 1s²2s²2p⁶3s²3p⁶

Electronic configuration of Fe⁺³ = [Ar]3d⁵

Outer electronic configuration of Fe⁺³ = 3d⁵

Oxidation number of Fe is +3

Hybridization is d²sp³

Since, CN^- is a strong field ligand so it pairs up the electron.

Thus, total no. of unpaired electrons = 1

We know,

Spin only magnetic moment is given by:

μ = [n(n + 2)]^1/2

μ = [1×3]^1/2 [As, unpaired electrons are 1]

μ = 1.732BM

Therefore, we can see that spin only magnetic moment of [Fe(H₂O)₆]³⁺ is more than [Fe(CN)₆]^3- .

so, [Fe(H₂O)₆]³⁺ is strongly paramagnetic whereas [Fe(CN)₆]³ weakly paramagnetic.

Due to resonance in phenol (C₆H₅OH), the C-O bond in phenols acquire a partial double bond character. Therefore the C-O bond in phenols is stronger than the C-O single bond in aliphatic alcohols (R-OH, where R is an alkyl group). Consequently it becomes difficult to break the C-O bond in phenols. So, arylhalides can not be prepared by reaction of phenol with HCl in the presence of ZnCl₂.

Resonance in phenol

Novolac is prepared from phenol (C₆H₅OH) and formaldehyde (HCHO). It is thus known as phenol-formaldehyde resin commonly as Bakelite. Novolac on heating with formaldehyde (HCHO) undergoes cross linking to form an infusible mass called bakelite.

Antidepressant drugs counteract the feeling of depression by balancing the chemicals known as neurotransmitters and triggering the hormones responsible for mood swings. Due to less release of the chemicals in brain depression is caused so these antidepressants act in these chemicals and increase their activity.

For example: Meprobromate, Equanil etc.

Both the components start coming to distillate as they would have formed an azeotropic mixture. Azeotropes are the binary mixtures having the same composition in liquid and vapor phase and boil at constant temperature. So it is not possible to separate them by distillation.

The cathode and anode are separated by a salt bridge. Anode is represented by the first half and cathode by the second one.

ANODE: Cu to Cu²⁺

CATHODE: Cl^- to Cl₂

REDUCTION HALF REACTION: Cl^- + 2e^-→ Cl₂

OXIDATION HALF REACTION: Cu → Cu²⁺ + 2e^-

To separate two sulphide ores for example there is an ore containing zinc sulphide and lead sulphide so when we add depressant that is NaCN or KCN then this selectively allows lead sulphide to come with the froth and prevents zinc sulphide to come with the froth.

P₄ + 6Cl₂ → 4PCl₃

PCl₃ + 3H₂O → H₃PO₃ + 3HCl} x 4

Overall reaction will be,

P₄ + 6Cl₂ + 12H₂O → 4 H₃PO₃ + 12HCl

1 mole of white phosphorus produces 12 moles of HCl…………..a)

1 mole of HCl weighs 36.5g,

so weight of 12moles will be, 12 x 36.5=438g……………………………i)

1 mole of white phosphorus weighs 124 g………………….ii)

Equation a) implies that 124g of phosphorus is used to produce 438g of HCl

So 1g of phosphorus would give= 438/124 g of HCl

62 g would give= (438/124) x 62 = 219 g of HCl

As two ions are produced in a solution and 1 mole AgCl is precipitated out so Cl would be present outside the bracket of the coordination compound and is the counter anion.

The structural formula of the compound is [Cr(H₂O)₄Cl₂]Cl .

While naming the compound since the counter anion Cl carries a negative charge, therefore the charge on the complex will be one. As there are 2 chloride ions both having a total of -2 charge, water is neutral so zero and 1 charge being on the ligand so the oxidation number of chromium would be,

X+0-2=1

X=3 is the oxidation number.

Name of the compound is tetraaquadichromium(III)Chloride.

(B)-Benzyl chloride would undergo faster S_N1 than (A)-Chloromethyl cyclohexane as the carbocation formed from benzyl chloride is resonance stabilized. In the case of chloromethyl cyclohexane the carbocation formed is primary. Primary carbocations are not favored by S_N1 reactions as a result it will not undergo S_N1 reaction as fast as the benzyl chloride.

Di tertiary butyl ether cannot be prepared by this method because when we take tertiary butyl halide then elimination competes over substitution. Due to this only an alkene is formed and no ether is obtained.

(CH)₃CO^-Na⁺ + (CH₃)₃CCl → (CH₃)₂C=CH₂

No ether is formed as a product.

i)Using Hoffmann bromamide degradation reaction we will get amine.

ii)By alkylation of the amine

Mechanism:

The nitrogen of amine acts as a nucleophile and attacks the carbon of alkyl halide as it is an electrophile. It displaces the halogen and forms a bond with carbon. Amines react through S_N2 mechanism.

CH₃ –Br → CH₃⁺ + Br ^–

ATTACKING OF NITROGEN OF AMINE

I and III have the C1 and C4 linkage between them whereas the II compound has a C1 and C6 linkage between them.

Yes compound I is a reducing sugar as C1 of glucose in solution is free and shows reducing properties.

Compound I is lactose.

Molarity is given by,

M= no. of moles/ volume of the solution.

As volume is directly proportional to temperature and inversely proportional to molarity, therefore molarity and temperature are inversely proportional.

The molarity of a solution can be changed by changing the volume. So this makes assertion and reason both correct and reason is the correct explanation.

Nitro group is an electron withdrawing group and its presence on the ortho and para position of the ring results in the decrease of the electron density of the OH bond due to which the H⁺ ion can be released easily. The nitro group stabilizes the phenoxide ion by dispersal of negative charge due to resonance. But in case of phenol no such group is present so p-nitrophenol is more acidic than phenol.

The most probable Kinetic energy and energy of activation affected with increase in temperature as according to Maxwell Boltzmann energy distribution curve when temperature T becomes T+10 degree Celsius then the effective collision and energy of molecules increases resulting in the formation of product.

OR

Difference between instantaneous rate of a reaction and average rate of a reaction.

Deep blue solution

Ca(OH)₂ + CO₂→ CaCO₃ (E) + H₂O

CaCO₃ + H₂O → Ca(HCO₃)₂

A= Copper sulphate

B= copper nitrate

C= Tetraamminecopper(II) sulphate

D=Carbon Dioxide

E= Calcium Carbonate

OR

KM_nO₄ is a violet compound of manganese and liberates oxygen as well as two other compounds.

Compound C is M_nO₂ which reacts with KOH in the presence of KNO₃ to give compound KM_nO₄.

It is given by the reaction,

A-Potassium Permanganate

B-Potassium Manganate

C- Manganese dioxide

D- Manganese chloride

Molecular formula is C₅H₁₀ and compound B gives positive iodoform that means a –COCH₃ group is present and it is an aldehyde as it gives positive Fehling’s Test. Therefore, the compound B is CH₃CHO. So after ozonolysis the two compounds that are formed are

(2-Methylbut-2-ene) (ethanal) (propanone)

A- 2-Methylbut-2-ene

B- Ethanol

C- Propanone

OR

Ethanal has an alpha hydrogen which undergo aldol reaction to form a product. Due to the strong electron withdrawing effect of the carbonyl group and resonance stabilization of the conjugate base, the alpha hydrogens are acidic in nature.

a)

This reaction is known as the cross-canizzaro’s reaction.

b)

This type of reaction is the Cannizaro’s reaction.