Students can use CBSE Previous Year Question Papers Class 12 Chemistry with Solutions and CBSE Class 12 Chemistry Question Paper 2014 Delhi to familiarize themselves with the exam format and marking scheme.
CBSE Class 12 Chemistry Question Paper 2014 Delhi with Solutions
General Instructions
- All questions are compulsory.
- Questions number 1 to 8 are very short answer questions and carry 1 mark each.
- Questions number 9 to 18 are short answer questions and carry 2 marks each.
- Questions number 19 to 27 are also short answer questions and carry 3 marks each.
- Questions number 28 to 30 are long answer questions and carry 5 marks each.
-
Use log tables if necessary. Use of calculators is not allowed.
\(\dagger\) Deleted from Syllabus.
Set I
Question 1.
Give one example each of ‘oil in the water’ and ‘water in oil’ emulsion. [1]
Answer:
Oil in water → Milk, vanishing cream
Water in oil → Butter, cold creams.
Question 2.
Which reducing agent is employed to get copper from the leached low-grade copper ore? [1]
Answer:
Hydrogen/Iron
Question 3.
Which of the following is more stable complex and why?
[Co(NH
3
)
6
]
3+
and [Co(en)
3
]
3+
[1]
Answer:
[Co(en)
3
]
3+
is more stable complex than [Co(NH
3
)
6
]
3+
because of chelate effect.
Question 4.
Write the IUPAC name of the compound. [1]
Answer:
IUPAC name : 3-Hydroxybutanoic acid
Question 5.
Which of the following isomers is more volatile:
o-nitrophenol or ph-nitrophenol? [1]
Answer:
o-nitrophenol is more volatile than p-nitrophenol due to intramolecular hydrogen bonding.
Question 6.
What are isotonic solutions? [1]
Answer:
An isotonic solution is a kind of solution with the same salt concentration as blood and cells. Those solutions which are exerting same osmotic pressure under similar conditions (For example 0.9% NaCl solution by mass volume is Isotonic with human blood).
Question 7.
Arrange the following compounds in increasing order of solubility in water: [1]
C
6
H
5
NH
2
, (C
2
H
5
)
2
NH, C
2
H
5
NH
2
Answer:
C
6
H
5
NH
2
< (C
2
H
5
)
2
NH < C
2
H
5
NH
2
Question 8.
Which of the two components of starch is water-soluble? [1]
Answer:
Amy lose is water soluble component of starch.
Question 9.
An element with density 11.2 gm cm
-3
forms f.c.c. lattice with edge length 4 × 10
-8
cm. Calculate the atomic mass of the element. (Given N
A
= 6.022 × 10
23
mol
-1
) [2]
Answer:
Given : d = 11.2 g cm
-3
, a = 4 × 10
-8
cm
For fcc lattice, z = 4
Question 10.
Examine the given defective crystal [2]
Answer the following questions:
(i) What type of stoichiometric defect is shown by crystal?
(ii) How is the density of the crystal affected by this defect?
(iii) What type of ionic substances shows such a defect?
Answer:
(i) Schottky defect
(ii) Density of the crystal decreases
(iii) NaCl (Ionic solids having approximate equal size of cations and anions)
Question 11.
Calculate the mass of compound (molar mass = 256 g mol
-1
) to be dissolved in 75 g of benzene to lower its freezing point by 0.48 K (K
f
= 5.12 K kg mol
-1
). [2]
Answer:
Given : ∆T
f
= 0.48K, W
1
= 75 g, M
2
= 256 g mol
-1
K
f
= 5.12 K kg mol
-1
W
2
= ?
Using formula, W
2
= \(\frac{\mathrm{M}_2 \times \mathrm{W}_1 \times \Delta \mathrm{T}_f}{1000 \times \mathrm{K}_f}\)
= \(\frac{256 \times 75 \times 0.48}{1000 \times 5.12}\) = 1.8 g
Question 12.
Define an ideal solution and write one of its characteristics. [2]
Answer:
Those solutions which are obeying Raoult’s law are called ideal solutions. An ideal solution is a solution in which no volume change and no enthalpy change takes place on mixing the solute and the solvent in any proportion.
Characteristic of ideal solution :
There will be no change in enthalpy ∆H
mixing
= 0, ∆V
mix
= 0, ∆P
mix
= 0
Question 13.
Write two differences between ‘order of reaction’ and ‘molecularity of reaction’. [2]
Answer:
| Order of reaction | Molecularity of reaction |
| 1. It is the sum of the concentration terms on which the rate of reaction actually depends. | It is the number of atoms, ions or molecules that must collide with one another simultaneously so as to result into a chemical reaction. |
| 2. It can be fractional as well as zero. | It can never be zero. |
Question 14.
Outline the principles behind the refining of metals by the following methods: [2]
(i) Zone refining method
(ii) Chromatographic method
Answer:
(i) Zone refining method : It is based on the principle that the impurities are more soluble in melt than in the solid state of the metal.
(ii) Chromatographic method : Principle—It is based on the principle that different components of a mixture are differently adsorbed on the adsorbent.
Question 15.
Complete the following chemical equations: [2]
(i) Ca
3
P
2
+ H
2
O →
(ii) Cu + H
2
SO
4
(conc.) →
OR
Arrange the following in order of property indicated against each set:
(i) HF, HCl, HBr, HI: increasing bond dissociation enthalpy
(ii) H
2
O, H
2
S, H
2
Se, H
2
Te: increasing acidic character.
Answer:
(i) Ca
3
P
2
+ 6H
2
O → 2PH
3
+ 3Ca(OH)
2
(ii) Cu + 2H
2
SO
4
(cone.) → CuSO
4
+ 2H
2
O + SO
2
Or
(i) HI < HBr < HCl < HF
(ii) H
2
O < H
2
S < H
2
Se < H
2
Te
Question 16.
Write the IUPAC name of the complex [Cr(NH
3
)
4
Cl
2
]
+
. What type of isomerism does it exhibit? [2]
Answer:
IUPAC name : Tetraamine dichlorido chromium (III) ion.
It exhibits geometrical isomerism.
Question 17.
(i) Which alkyl halide from the following pair is chiral and undergoes faster S
N
2 reaction? [2]
(ii) Out of S
N
1 and S
N
2, which reaction occurs with
(a) Inversion of configuration
(b) Racemisation
Answer:
(i) 2-bromobutane
is a chiral compound and 1 Bromo Butane undergoes S
N
2 reaction faster.
(ii) (a) Inversion of configuration occurs with S
N
2 reaction.
(b) Racemisation occurs with S
N
1 reaction.
Question 18.
Draw the structure of major moon halo product in each of the following reactions: [2]
Answer:
Question 19.
(a) In reference to Freundlich adsorption isotherm, write the expression for adsorption of gases on solids in the form of an equation. [3]
(b) Write an important characteristic of lyophilic sols.
(c) Based on the type of particles of the dispersed phase, give one example each of associated colloid and multimolecular colloid.
Answer:
(a) The equation representing adsorption of gases on solids is
\(\frac{x}{m}\) = KP
1/n
Where
[x / m = amount of gas adsorbed per unit mass of adsorbent
K = Constant
n = Positive integer
(b) Lyophilic sols are reversible and self stable.
(c) Associated colloid : Soap sol
Multimolecular colloid : Gold sol
Question 20.
(a) Draw the structures of the following molecules: [3]
(i) XeOF
4
(ii) H
2
SO
4
(b) Write the structural difference between white phosphorus and red phosphorus
Answer:
(a) (i) XeOF
4
:
(ii) H
2
SO
4
(b) White phosphorus exists as discrete P
4
units with SP
3
hybridized phosphorus atom, arranged tetrahedrally but in red phosphorus all P
4
tetrahedral units linked with each other to form polymeric structure
Question 21.
Account for the following: [3]
(i) PCl
5
is more covalent than PCl
3
.
(ii) Iron on reaction with HCl forms FeCl
2
and not FeCl
3
.
(iii) The two O-O bond lengths in the ozone molecule are equal.
Answer:
(i) In PCl
5
, phosphorus has +5 oxidation state and has less tendency to lose electrons than in +3 of PCl
3
. Therefore, in PCl
5
has more tendency to share e
-1
than PCl
3
.
(ii) Because HCl on reaction with Iron liberates H
2
gas which prevents the formation of ferric chloride.
(iii) Due to resonance the two oxygen atoms have partial double bond character and thus have same bond length i.e. 128 pm
Question 22.
The following data were obtained during the first order thermal decomposition of SO
2
Cl
2
at a constant volume: [3]
SO
2
Cl
2
→ SO
2
+ Cl
2
Calculate the rate constant.
(Given: log 4 = 0.6021, log 2 = 0.3010)
Answer:
Question 23.
(i) Give two examples of macromolecules that are chosen as drug targets. [3]
(ii) What are antiseptics ? Give an example.
(iii) Why is the use of aspartame limited to cold foods and soft drinks?
Answer:
(i) Carbohydrates and proteins
(ii) Antiseptics : These are chemical substances which prevent the growth of micro-organisms and may even kill them-and safe to be applied on living tissues.
Example : Furacin, soframycin etc.
(iii) Because it decomposes at baking or cooking temperature.
Question 24.
(i) Deficiency of which vitamin causes night blindness?
(ii) Name the base that is found in the nucleotide of RNA only.
(iii) Glucose on reaction with HI gives n-hexane.
What does it suggest about the structure of glucose? [3]
Answer:
(i) Vitamin A causes night blindness.
(ii) Uracil is found in nucleotide of RNA only.
(iii) It suggests the open structure of glucose.
Question 25.
After the ban on plastic bags, students of a school decided to make the people aware of the harmful effects of plastic bags on the environment and Yamuna River. To make the awareness more impactful, they organized rally by joining hands with other schools and distributed paper bags to vegetable vendors, shopkeepers and departmental stores. All the students pledged not to use polythene bags in the future to save the Yamuna River. [3]
After reading the above passage, answer the following questions:
(i) What values are shown by the students?
(ii) What are bio-degradable polymers? Give one example.
(iii) Is polythene a condensation or the addition polymer?
Answer:
(ii) Those polymers which can be decomposed by microorganisms are called biodegradeable polymers.
Example : Nylon-2-Nylon-6
(iii) Polythene is an addition polymer.
Question 26.
(a) Write the mechanism of the following reaction: [3]
(b) Write the equation involved in Reimer Tiemann reaction.
Answer:
(a)
(b) Reimer Tiemann reaction:
Question 27.
Give the structures of A, B and C in the following reactions: [3]
OR
How will you convert the following?
(i) Nitrobenzene into aniline.
(ii) Ethanoic acid into methenamine.
(iii) Aniline into N-phenylethanamide.
(Write the chemical equations involved.)
Answer:
Or
(i) Nitrobenzene into aniline
(ii) Ethanoic acid into methanamine
(iii) Aniline into N-phenylethanamide
Question 28.
(a) Define the following terms:
(i) Limiting molar conductivity
(ii) Fuel cell
(b) The resistance of a conductivity cell filled with 0.1 mol L
-1
KCl solution is 100 Ω. If the resistance of the same cell when filled with 0.02 mol L
-1
KCl solution is 520 Ω, calculate the conductivity and molar conductivity of 0.02 mol L
-1
KCl solution. The conductivity of 0.1 mol L
-1
KCl solution is 1.29 × 10
-1
Ω
-1
cm
-1
.
OR
(a) State Faraday’s first law of electrolysis. How much charge in terms of Faraday is required for the reduction of 1 mol of Cu
2+
to Cu.
(b) Calculate emf of the following cell at 298 K:
Mg(s) | Mg
2+
(0.1M) | | Cu
2+
(0.01 M) | Cu(s)
[Given E
0
cell
= +2.71 V, 1F = 96500 C mol
-1
] [5]
Answer:
(a) (i) Limiting molar conductivity : The molar conductivity of a solution at infinite dilution is called limiting molar conductivity and is represented by the symbol \(\Lambda_{\mathrm{m}}^{\circ}\)
(ii) Fuel cell :
These cells are the devices which convert the energy produced during combustion of fuels lilce H
2
, CH
4
, etc. directly into electrical energy.
(b) For 0.1 M KCl solution
R = 100 Ω, K = 1.29 × 10
-2
Ω
-1
cm
-1
Formula : Cell constant = Conductivity × Resistance
= 1.29 × 10
-2
× 100 = 1.29 cm
-1
or 129
-1
For 0.2 M KCI solution, conductivity
Or
(a) According to first law of Faraday’s “the amount of chemical reaction and hence the mass of any substance deposited/liberated at any electrode is directly proportional to the quantity of electricity passed through the electrolyte.”
The quantity of charge required for reduction of 1 mol of Cu
2+
= 2 faradays (∵ Cu
2+
+ 2
e-
→ Cu)
= 2 × 96500 C = 193000 C
(b) Cell reaction : Mg + Cu
2+
Mg
2+
+ Cu (n = 2)
Using Nernst equation,
Question 29.
(a) How do you prepare: [2, 3]
(i) K
2
MnO
4
from MnO
2
(ii) Na
2
Cr
2
O
7
from Na
2
CrO
4
(b) Account for the following:
(i) Mn
2+
is more stable than Fe
2+
towards oxidation to +3 state.
(ii) The enthalpy of atomization is lowest for Zn in 3d series of the transition elements.
(iii) Actinoid elements show a wide range of oxidation states.
OR
(i) Name the elements of 3d transition series which shows the maximum number of oxidation states. Why does it show so?
(ii) Which transition metal of the 3d series has positive E°(M
2+
/M) value and why?
(iii) Out Of Cr
3+
and Mn
3+
, which is a stronger oxidizing agent and why?
(iv) Name a member of the Lanthanoid series which is well known to exhibit +2 oxidation state.
(v) Complete the following equation
MnO
4
–
+ 8H
+
+ 5e
–
→
Answer:
(a) (i) Finely powdered pyrolusite is fused with KOH in the presence of air to give green coloured potassium manganate.
(ii) Na
2
Cr
2
O
7
from Na
2
CrO
4
(b) (i) Due to stable half-filled 3d
5
configuration of Mn
2+
/high 3
rd
ionisation enthalpy of Mn, Mn
2+
is much more resistant than Fe2 towards oxidation.
(ii) As there are no unpaired electrons in zinc, it is soft and has low melting point and low enthalpy of atomization.
(iii) Because of very small energy gap between 5f, 6d and 7s subshells all their electrons can take part in bonding and shows variable oxidation states.
Or
(i) Manganese. Due to presence of more unpaired electrons and use of all 4s and 3d electrons in the middle of series.
(ii) Copper has positive E°(Cu
2+
/Cu) value because of its high enthalpy of atomization and low enthalpy of hydration. The high energy required to oxidise Cu to Cu
2+
is not balanced by its hydration energy.
(iii) Cr
2+
has the configuration 3d
4
which easily changes to d
3
due to stable half filled t
2
g orbitals. Therefore Cr
2+
is reducing agent. While Mn
2+
has stable half filled d
5
configuration. Hence Mn
3+
easily changes to Mn
2+
and acts as oxidising agent.
(iv) Eutropium is well known to exhibit +2 oxidation state.
(v) Mn\(\mathrm{O}_4^{-}\) + 8H
+
+ 5e
–
→ Mn
2+
+ 4H
2
O
Question 30.
(a) Write the products of the following reactions: [2, 3]
(i)
(ii) 2C
6
H
5
CHO + conc. NaOH →
(iii) CH
3
COOH \(\xrightarrow{\mathrm{Cl}_2 / \mathrm{P}}\)
(b) Give simple chemical tests to distinguish between the following pairs of compounds:
(i) Benzaldehyde and Benzoic acid
(ii) Propanal and Propanone
OR
(a) Account for the following:
(i) CH
3
CHO is more reactive than CH
3
COCH
3
towards reaction with HCN.
(ii) Carboxylic acid is a stronger acid than phenol.
(b) Write the chemical equations to illustrate the following name reactions:
(i) Wolff-Kishner reduction
(ii) Aldol condensation
(iii) Cannizzaro reaction
Answer:
(a)
(b)
(i) Benzaldehyde and benzoic acid
Or
(a) (i) Aldehydes are more reactive than ketones due to the following two reasons :
1. Manganese due to smaller +I effect of one alkyl group in aldehydes as compared to larger +I effect of two alkyl groups. the magnitude of positive charge on the carbonyl carbon is more in aldehydes than in ketones, As a result, nucleophilic addition reactions occur more readily in aldehydes than in ketones.
2. Due to presence of a H-atom on the carbonyl group, aldehydes can be more easily oxidised than ketones.
(ii) The release of a proton from carboxylic acid is much easier than phenols because carboxylate ion is much more resonance stabilized than phenoxide ion.
(b) (i) Wolff-Kishner reduction :
The reduction of aldehydes and ketones to the corresponding hydrocarbons by heating them with hydrazine and KOH or pot. tert-butoxide in a high boiling solvent like ethylene glycol is called Wolff—Kishner reduction.
(ii) Aldol condensation : In these two molecules of aldehydes or ketones containing α-hydrogen atoms on treatment with dil. NaOH undergo condensation to form β-hydroxyaldehydes or β-hydroxy ketones
(iii) Cannizzaro reaction :
Aldehydes, which do not have an a-hydrogen atom undergo self oxidation and reduction on treatment with conc. alkali and produce alcohol and carboxylic acid salt.
Set II
Note: Except for the following questions, all the remaining questions have been asked in the previous se t.
Question 1.
Give one example each of sol and gel. [1]
Answer:
Sol → Smoke, dust
Gel → Cheese
Question 3.
Write the IUPAC name of the compound [1]
Answer:
TUPAC name :3-Aminobutanal
Question 5.
Some liquids on mixing form ‘azeotropes’. What are ‘azeotropes’? [1]
Answer:
The liquid mixture having a definite composition and boiling like a pure liquid without change in composition is called as azeotrope.
Question 6.
Arrange the following in increasing order of basic strength:
C
6
H
5
NH
2
, C
6
H
5
NHCH
3
, C
6
H
5
CH
2
NH
2
Ans.
C
6
H
5
NH
2
< C
6
H
5
NHCH
3
< C
6
H
5
CH
2
NH
2
Question 7.
Which component of starch is a branched polymer of a-glucose and insoluble in water? [1]
Answer:
Amylopectin.
Question 9.
State Henry’s law. What is the effect of temperature on the solubility of a gas in a liquid? [2]
Answer:
Henry’s law states that, “The solubility of a gas in a liquid at a particular temperature is directly proportional to the pressure of the gas in equilibrium with the liquid at that temperature.”
Solubility of gas decreases with increase of temperature at the same pressure.
Question 10.
Define the following terms: [2]
(i) Pseudo-first-order reaction
(ii) The half-life period of reaction (t1/2).
Answer:
(a) Those reactions which are not truly of the first order but under certain conditions become first order reactions are called pseudo first order reaction.
(b) The time taken for half of the reaction to complete is called half life period.
Question 11.
Write the principle behind the following methods of refining: [2]
(i) Hydraulic washing
(ii) Vapour-phase refining
Answer:
(i) Hydraulic washing or Levigation : The process is based on the principle that lighter earthy particles are removed from heavier ore particles by washing with water (Difference in the gravities).
(ii) Vapour phase refining: In this method, the crude metal is freed from impurities by first converting it into a suitable volatile compound by heating with a specific reagent at a lower temperature and then decomposing the volatile compound at some higher temperature to give the pure metal.
Question 22.
(a) Draw the structures of the following: [3]
(i) XeF
2
(ii) BrF
3
(b) Write the structural difference between white phosphorus and red phosphorus.
Answer:
(a) (i)
(ii) BrF
3
:
(b) White phosphorus exists as discrete P
4
units with SP
3
hybridized phosphorus atom, arranged tetrahedrally but in red phosphorus all P
4
tetrahedral units linked with each other to form polymeric structure
Question 23.
Account for the following: [3]
(i) Bi(V) is a stronger oxidizing agent than Sb(V).
(ii) N – N single bond is weaker than the P – P single bond.
(iii) Noble gases have very low boiling points.
Answer:
(i) Bi(V) is a stronger oxidizing agent than Sb(V) due to inert pair effect as the stability of lower oxidation state (+3) increases down the group.
(ii) Due to smaller size of Nitrogen. their lone pairs repel the bond pair of N — N bond while P — P due to bigger size does not show more repulsion.
(iii) Due to presence of weak Vander waal forces of attraction, noble gases have very low boiling point.
Question 24.
(i) Name the sweetening agents used in the preparation of sweets for a diabetic patient. [3]
(ii) What are antibiotics? Give an example.
(iii) Give two examples of macromolecules that are chosen as drug targets.
Answer:
(i) Saccharin is used for a diabetic patient for preparation of sweets.
(ii) Antibiotics: Those chemical substances which are produced completely or partially by chemical synthesis in low concentration and either kill or inhibit the growth of micro-organisms by intervening in their metabolic processes, are known as antibiotics.
Example Tetracycline, Vancomycin
(iii) (i) Carbohydrates and proteins
(ii) Antiseptics : These are chemical substances which prevent the growth of micro organisms and may even kill them-and safe to be applied on living tissues.
Example : Furacin, soframycin etc.
(iii) Because it decomposes at baking or cooking temperature.
Question 27.
(i) Deficiency of which vitamin causes rickets? [3]
(ii) Give an example for each of fibrous protein and globular protein.
(iii) Write the product formed on reaction of D-Glucose with Br
2
water.
Answer:
(i) Deficiency of Vitamin D causes rickets,
(ii) Fibrous protein → α-keratin
Globular protein → Insulin
(iii)
Set III
Note: Except for the following questions, all the remaining questions have been asked in previous sets.
Question 1.
Give one example each of lyophobic sol and lyophilic sol. [1]
Answer:
Lyophobic sol — Metal sulphides
Lyophilic sol — Starch
Question 2.
Write the IUPAC name of the compound. [1]
Answer:
IUPAC name : 4-Hydroxypentan-2 -one
Question 3.
What type of intermolecular attractive interaction exists in the pair of methanol and acetone? [1]
Answer:
Solute-solvent dipolar interactions exist in the pair of methanol and acetone.
Question 5.
Arrange the following in increasing order of basic strength:
C
6
H
5
NH
2
, C
6
H
5
NHCH
3
, C
6
H
5
N(CH
3
)
2
Answer:
C
6
H
5
N(CH
3
)
2
> C
6
H
5
NHCH
3
> C
6
H
5
NH
2
Question 6.
Name the products of hydrolysis of sucrose. [1]
Answer:
Glucose and fructose are the products of hydrolysis of sucrose.
Question 9.
State Raoult’s law for the solution containing volatile components. What is the similarity between Raoult’s law and Henry’s law? [2]
Answer:
Raoult’s law : “In a solution, the vapour pressure of a component at a given temperature is equal to the mole fraction of that component in the solution multiplied by the vapour pressure of that component in pure state.”
Similarity between Raoult’s law and Henry’s law is that the partial pressure or vapour pressure of the volatile component (gas) is directly proportional to the mole fraction of that component in the solution.
Question 10.
Explain the following terms: [2]
(i) The rate constant (k)
(ii) The half-life period of reaction (t
1/2
).
Answer:
(i) Rate constant (k) : It is a proportionality constant and is equal to the rate of reaction when the molar concentration of each of the reactants is unity.
(ii) Half life period of a reaction (t
1/2
) : The time taken for half of the reaction to complete is called half life period.
Question 11.
Write the principles of the following methods: [2]
(i) Froth floatation method
(ii) Electrolytic refining
Answer:
(i) Froth floatation process : This method is used for removing gangue from suiphide ores. In this powdered ore is mixed with collectors (e.g. pine oils, fatty acids etc.) and froth stabilisers (e.g. cresols, aniline) which enhance non-wettability of the mineral particles and froth stabilisation respectively. As a result of which ore comes with froth and gangue remain in the solution.
(ii) Electrolytic refining: Here the impure metal is made to act as anode and a strip of the same metal in pure form is used as cathode. When they both are put in suitable electrolyte containing soluble salt of same metal, the more basic metal remains in the solution and the less basic ones go to the anode mud.
Example: In refining of Cu
At anode: (oxidation)
Cu → Cu
2+
+ 2e
–
At cathode : (reduction)
Cu
2+
+ 2e
–
→ Cu
Question 20.
(a) Draw structure of the following compounds:
(i) XeF
4
(ii) N
2
O
5
(b) Write the structural difference between white phosphorus and red phosphorus. [3]
Answer:
(a) (I) XeF
4
:
(ii) N
2
O
5
:
(b) White phosphorus exists as discrete P
4
units with SP
3
hybridized phosphorus atom, arranged tetrahedrally but in red phosphorus all P
4
tetrahedral units linked with each other to form polymeric structure
Question 22.
Account for the following:
(i) Sulphur in vapour form exhibit paramagnetic behaviour.
(ii) SnCl
4
is more covalent than SnCl
2
.
(iii) H
3
PO
2
is a stronger reducing agent than H
3
PO
3
. [2]
Answer:
(i) In vapour state sulphur partly exists as S
2
molecule which has two unpaired electrons in the antibonding π orbitals and hence exhibits paramagnetism.
(ii) Sn
+4
in SnCl
4
has more polarising power than (Sn
+2
) in SnCl
2
(iii) H
3
PO
2
contains two P-H bonds while H
3
PO
3
cõntains only one P-H bond therefore H
3
PO
2
is stronger reducing agent.
Question 23.
(i) What are disinfectants? Give an example. [3]
(ii) Give two examples of macromolecules that are chosen as drug targets.
(iii) What are anionic detergents? Give an example.
Answer:
(i) Disinfectants : They are chemical substances which kill micro-organisms. They are not safe to be applied to the living tissues. They are used to kill micro-organisms present in the drains, toilets, floors etc.
Example: Phenol (≥ 1% solution) and chlorine (0.2 to 0.4 ppm).
(ii) Macromolecules used as drug targets are carbohydrates, proteins, nucleic add and lipids.
(iii) Anionic detergents.
Those detergents in which large part of their molecules are anions and used in cleansing action, are called anionic detergents.
Example: Sodium alkyl sulphates
These are obtained from long straight chain alcohols containing 12-18 carbon atoms by treatment with conc. H
2
SO
4
followed by neutralization with NaOH.
Example: Sodium lauryl sulphate.
Question 24.
(i) Deficiency of which vitamin causes scurvy?
(ii) What type of linkage is responsible for the formation of proteins?
(iii) Write the product formed when glucose is treated with HI. [3]
Answer:
(i) Vitamin C causes scurvy.
(ii) Peptide linkages are responsible for the formation of proteins.
(iii) With HI :
