ISC (Science)
Academic Year: 2024-2025
Date: एप्रिल 2025
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- You are allowed additional 15 minutes for only reading the question paper.
- You must NOT start writing during the reading time.
- This question paper has 11 printed pages.
- It is divided into four sections and has 21 questions in all.
- All questions are compulsory. Answer all questions.
- Section A has fourteen subparts. Each question carries 1 mark.
- While attempting Multiple Choice Questions in Section A, you are required to write only ONE option as the answer.
- Section B has ten questions. Each question carries 2 marks.
- Section C has seven questions. Each question carries 3 marks.
- Section D has three questions. Each question carries 5 marks.
- Internal choices have been provided in one question each in Sections B, C and D.
- The intended marks for questions are given in brackets [ ].
- All working, including rough work, should be done on the same sheet as, and adjacent to the rest of the answer.
- Balanced equations must be given wherever possible and diagrams where they are helpful.
- When solving numerical problems, all essential workings must be shown.
- In working out problems, use the following data:
Gas constant R = 1.987 cal deg-1 mol-1 = 8.314 JK-1mol-1
= 0.0821 dm3 atm K-1 mol-1, 1 l atm = 1 dm3 atm = 101.3 J.
1 Faraday = 96500 coulombs. Avogadro’s number= 6.023 × 1023.
The molar conductance of a solution _______ with dilution, while its specific conductance _______ with dilution.
increases
formic acid
decreases
less
zero
small
paired
atoms
unpaired
ions
pentagonal bipyramidal
electrical
more
ethylamine
molecules
propanoic acid
methylamine
chemical
Chapter: [0.064] Electrolytic conductance
In the complex ion \[\ce{[CoCl(en)2ONO]+}\], the coordination number and the oxidation number of the central metal ion are ______ and ______.
four
three
remains same
propane
ns1-2
increases
six
propan-2-ol
(n-1)d1-10
two
decreases
Clemmensen’s
Wolff-Kishner
Chapter: [0.07] Coordination Compounds
Propanone on reaction with zinc amalgam in the presence of conc. HCI gives ______ and the reaction is known as ______ reduction.
stable
low
aldehyde
unstable
6
4
ethane
Clemmensen’s
2
3
carboxylic acid
high
propane
Rosenmund's
Chapter: [0.131] Carbonyl compounds
The variation and magnitude of oxidation state in coordination complexes is due to the participation of inner ______ electrons in addition to outer ______ electrons.
four
three
remains same
propane
ns1-2
increases
six
propan-2-ol
(n-1)d1-10
two
decreases
Clemmensen’s
Wolff-Kishner
Chapter: [0.07] Coordination Compounds
The correct order of the increasing basic nature of Ammonia, Methylamine and Aniline is:
Methylamine < Aniline < Ammonia
Aniline < Methylamine < Ammonia
Ammonia < Aniline < Methylamine
Aniline < Ammonia < Methylamine
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
Colligative properties of a solution are:
(P) Independent of the nature of solute
(Q) Proportional to molecular mass of solute
(R) Proportional to concentration of solute
(S) Independent of the amount of solvent
Only P and Q are correct.
Only P and R are correct.
Only P and S are correct.
Only Q and S are correct.
Chapter: [0.013000000000000001] Relative molecular mass of non-volatile substances
According to Markownikoff’s rule, “The negative part of the halogen acid attaches itself with that C atom of an unsymmetrical alkene which has least number of H-atom.”
Anti-Markownikoff’s addition of HBr is NOT observed in:
Propene
But-2-ene
But-1-ene
Pent-2-ene
Chapter: [0.113] Preparation, properties, uses of haloalkanes
Most of the naturally occurring α-amino acids are optically active and have L-configuration. Which of the following amino acids is NOT asymmetric?
Valine
Alanine
Glycine
Leucine
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
Which one of the following complex ions has geometrical isomers?
\[\ce{[Ni(NH3)5Br]+}\]
\[\ce{[Cr(NH3)4en]^3+}\]
\[\ce{[Co(NH3)2(en)2]^3+}\]
\[\ce{[Co(NH3)6]^3+}\]
Chapter: [0.07] Coordination Compounds
Assertion: Tertiary butyl bromide undergoes Wurtz reaction to give 2,2,3,3 tetramethyl butane.
Reason: In Wurtz reaction, when same alkyl halides react with sodium in dry ether to give hydrocarbon; the hydrocarbon formed contains double the number of carbon atoms present in the alkyl halide.
Both Assertion and Reason are true and Reason is the correct explanation of assertion.
Both Assertion and Reason are true but Reason is not the correct explanation for Assertion.
Assertion is true but Reason is false.
Both Assertion and Reason are false.
Chapter: [0.114] Chlorobenzene
Assertion: There is a continuous increase in size among Lanthanoids with an increase in atomic number.
Reason: Lanthanoids do not show Lanthanoid contraction.
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Both Assertion and Reason are true but Reason is not the correct explanation for assertion.
Assertion is true but Reason is false.
Both Assertion and Reason are false.
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
Read the passage carefully and answer the questions that follow.
|
A plant or any other living being maintains a reasonable balance of C-14 (radioactive carbon) in its tissue during its lifetime. C-14 is used to determine the age of fossils. In the upper atmosphere, neutrons present in the cosmic rays are captured to produce the following nuclear reaction. \[\ce{_7N^14 + _0n^1 -> _6C^14 + _1H^1}\] C-14 isotope circulates in the atmosphere and is absorbed by living organisms during photosynthesis. The ratio of C-14 to C-12 in living beings is 1 : 1012. Once a living being dies, the level of C-14 in the dead being decreases due to the following reaction. \[\ce{_6C^14 -> _7N^14 + _-1e^0 + γ rays}\] The death of the plant brings an end to its tendency to take up C-14. The half-life period of C-14 is 5770 years. By knowing the concentration of C-14 in the living plant and the piece of dead material at a particular time, the age of the material (fossil) can be determined. |
- Write the relation between the decay constant and half-life period.
- In a piece of dead wood, the activity or concentration of C-14 is found to be one third of its initial activity. Calculate the age of the old wood.
- The half-life period (t1/2) for a first order reaction is 30 minutes. Calculate the time taken to complete 87·5% of the reaction.
Chapter: [0.0301] Order of a reaction
The solution of two electrolytes A and B are diluted. ^m of B increases 1.5 times while that of A increases 25 times. Which of the two is a strong electrolyte? Give a reason.
Chapter: [0.064] Electrolytic conductance
An organic compound [A] which has characteristic odour, reacts with conc. NaOH to give two compounds [B] and [C]. Compound [B] has molecular formula C7H8O which upon oxidation gives back compound [A]. Compound [C] is the sodium salt of the acid and upon treatment with sodalime yields an aromatic hydrocarbon [D]. Identify the compounds [A], [B], [C] and [D].
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
Devise a scheme for the synthesis of n-butane using CH3I as the only source of carbon. Is it possible to obtain propane in pure state by applying this scheme? Give a reason for your answer.
Chapter: [0.114] Chlorobenzene
It is generally observed that the rate of a chemical reaction becomes double with every 10oC rise in temperature. If the generalisation holds true for a reaction in the temperature range of 298K to 308K, what would be the value of activation energy (Ea) for the reaction?
Chapter: [0.0305] The concept of energy
An organic compound [X] of molecular formula C3H5N, in one reaction produced a primary amine with LiAlH4. In another case, the organic compound [Y] of same molecular formula C3H5N produced a secondary amine with LiAlH4. Identify both the compounds [X] and [Y]. Why do these compounds form two different products?
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
During chemistry class, a teacher wrote \[\ce{[Ni(CN)4]^2-}\] as a coordination complex ion on the board. The students were asked to find out the magnetic behaviour and shape of the complex. Pari, a student, wrote the answer paramagnetic and tetrahedral whereas another student Suhail wrote diamagnetic and square planer.
Evaluate Pari’s and Suhail’s responses.
Chapter: [0.07] Coordination Compounds
An organic compound ‘X’ with molecular formula C4H10O is found to be soluble in conc. H2SO4 and does not react with sodium metal or KMnO4. Compound ‘X’ when heated with excess of HI gives a single alkyl halide. Deduce the structure of the compound ‘X’. Explain all the reactions involved.
Chapter: [0.121] Methods of preparation, manufacture, properties and use
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Identify the compound [A] and [B] in the following reaction.
\[\ce{C6H5CHO ->[(1) K2Cr2O7/H2SO4][(2) SOCl2] [A]->[C6H6(anhy.AlCl3)] [B]}\]
Chapter: [0.121] Methods of preparation, manufacture, properties and use
Identify the compound [A] and [B] in the following reaction.
\[\ce{CH3-C ≡ CH ->[(1) H2SO4/HgSO4][(2) vigorous oxidation,conc{.}HNO3][A]->[C2H5OH][{[{conc.} H_2SO_4]}][B]}\]
Chapter: [0.121] Methods of preparation, manufacture, properties and use
Three organic compounds A, B and C are non cyclic functional isomers of carbonyl compounds with molecular formula C4H8O. Isomers A and C give positive Tollen’s test while compound B does not give positive Tollen’s test but gives positive iodoform test. Compounds A and B on reduction with Zn amalgam and conc. HCl give the same product.
- Write the structures of the compounds A, B and C.
- Out of the compounds A, B and C, which one will be the least reactive towards addition of HCN.
Chapter: [0.07] Coordination Compounds
Calculate the value of \[\ce{E^\circ}\]cell, E cell and ΔG that can be obtained from the following cell at 298 K.
\[\ce{Al/Al^3+ _{(0.01 M)} // Sn^{2+} _{(0.015 M)}/Sn}\]
Given: \[\ce{E^\circ Al^3+/Al = -1.66 V; E^\circ\phantom{.}Sn^2+/Sn = -0.14 V}\]
Chapter: [0.062] Galvanic cells, mechanism of current production in a galvanic cell;
Write the chemical test to distinguish between Propan-1-ol and Propan-2-ol.
Chapter: [0.122] Preparation, properties and uses of ethane-1, 2 diol, propane-1, 2, 3 triol
Write a chemical test to distinguish between ethanol and phenol.
Chapter: [0.12300000000000001] Distinction between primary, secondary and tertiary alcohols
Identify the compounds [A], [B] and [C] in the following reaction.
\[\ce{C6H5NO2->[6{[H]}][Sn/HCl][A]->[HNO2 + HCl][273K-278K][B]->[C6H5NH2] [C]}\]
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
Identify the compounds [A], [B] and [C] in the following reaction.
\[\ce{CH3CH2NH2->[(1) HNO2][(2) P/Cl2][A]->[(1) KCN][(2) H2O/H+][B]->[(1) NH3/heat][(2) Br2/KOH][C]}\]
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
The molar mass calculated through colligative properties is sometimes different from that of experimentally determined molecular mass and is known as abnormal molecular mass. This difference is due to the solute particles that undergo association or dissociation.
Consider the two cases given below and answer the questions that follow.
- The freezing point of a solution containing 5.85g of NaCl in 100g of water is −3.348oC. (Kf of water = 1.86 K kg mol-1 , molecular mass of NaCl = 58.5)
- The freezing point of benzene solution decreases by 0.45oC when 0.2g of acetic acid is added to 20g of benzene. (Kf of benzene = 5.12 K kg mol-1 , molecular mass of acetic acid = 60)
Answer the following questions.
- Calculate the abnormal molecular mass of solute in both the cases.
- Inferring the value of van’t Hoff factor in both the cases, find out which solution undergoes association and which solution undergoes dissociation.
- Given below is the increasing order of depression in freezing point of water observed for equimolar concentrations of the compounds,
acetic acid < trichloro acetic acid < trifluoro acetic acid
Provide a reason to explain if the above ordered arrangement is correct or not.
Chapter: [0.013000000000000001] Relative molecular mass of non-volatile substances
Write a chemical equation to illustrate the following name reaction.
Rosenmund’s reaction
Chapter: [0.142] Acid derivatives
Write a chemical equation to illustrate the following name reaction:
Benzoin condensation
Chapter: [0.131] Carbonyl compounds
Write a chemical equation to illustrate the following named reaction:
Perkin's reaction
Chapter: [0.131] Carbonyl compounds
Assuming that cyanide is a strong ligand, write the formula of two coordination complex ions with cyanide and iron having coordination number six. Name the complex ions.
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
On the basis of Crystal Field Theory, write the electronic configuration of d4 ion if Δ0 > P.
Chapter: [0.07] Coordination Compounds
On the basis of crystal field theory, write the electronic configuration for d4 ion if ∆0 < P.
Chapter: [0.07] Coordination Compounds
Dry cells are commonly used in clocks, torches, calculators etc. They are the most familiar type of commercial cells.
- What acts as anode and cathode in dry cell?
- Which chemical compounds are filled between anode and cathode of this cell?
- Why do dry cells not have a long life?
Chapter: [0.062] Galvanic cells, mechanism of current production in a galvanic cell;
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What happens to the voltage when the salt bridge is removed from the two half cells and why?
Chapter: [0.062] Galvanic cells, mechanism of current production in a galvanic cell;
Copper sulphate solution cannot be stored in a zinc pot. Why?
Chapter: [0.062] Galvanic cells, mechanism of current production in a galvanic cell;
Why does the density of H2SO4 in a lead storage battery decrease as it is discharged?
Chapter: [0.065] Batteries
The structures of glycine and alanine are given below. Show the peptide bond linkage in glycylalanine.
\[\ce{\underset{Glycine}{H2N - CH2 - COOH}}\];
\[\begin{array}{cc}
\ce{CH3}\phantom{..}\\
|\phantom{.....}\\
\ce{\underset{Alanine}{H2N - CH - COOH}}\
\end{array}\]
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
What is reducing sugars?
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
Give an example of reducing sugar.
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
Consider the data given below for the reaction:
\[\ce{A + B-> Product}\]
| S. No. | conc. of [A] mol L-1 | conc. of [B] mol L-1 | Rate; mol L-1 sec-1 |
| 1. | 0.1 | 0.1 | 4.0 × 10-4 |
| 2. | 0.2 | 0.2 | 1.6 × 10-3 |
| 3. | 0.5 | 0.1 | 1.0 × 10-2 |
| 4. | 0.5 | 0.5 | 1.0 × 10-2 |
Answer the following questions.
- What is the order of reaction with respect to A and B?
- Calculate the rate constant.
- Determine the reaction rate when the concentration of A and B are 0.2 mol L-1 sec-1 and 0.35 mol L-1 sec-1 respectively.
Chapter: [0.031] Effect of concentration of reactants on the rate of a reaction
|
Phenol, one of the deadliest acids, contains a hydroxy group directly attached to the aromatic ring. A hydroxy group attached to an aromatic ring is also referred to as a phenolic group. Due to the presence of -OH group, phenols show many reactions similar to those of alcohols. The direct attachment of -OH group to the aromatic ring makes its behaviour very different from that of alcohols. That is why phenol behaves differently from alcohols in many reactions. The chemical reactions of phenol can be categorised as follows:
|
- Write the chemical equation for the preparation of phenol from benzene using H2SO4 and NaOH.
- What happens when phenol reacts with Br2/CS2 at low temperature?
- What is observed when phenol is treated with neutral ferric chloride solution?
- Write the reaction when phenol is treated with conc. HNO3 in the presence of conc. H2SO4.
- Write the reaction when phenol is treated with chloroform in the presence of aqueous NaOH at 340 K.
Chapter: [0.12300000000000001] Distinction between primary, secondary and tertiary alcohols
Give a reason for the following.
The purple colour of KMnO4 disappears in the presence of acidified solution of oxalic acid.
Chapter: [0.122] Preparation, properties and uses of ethane-1, 2 diol, propane-1, 2, 3 triol
Give a reason for the following.
Some transition metals and their compounds get attracted towards the magnetic field.
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
Why is Mn2+ ion more stable than Fe2+ ion?
(Atomic numbers of Mn = 25 and Fe = 26)
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
Complete and balance the following reaction.
\[\ce{KMnO4 + H2SO4 + FeSO4->}\] ______ + ______ + ______+ ______
Chapter: [0.115] Preparation, properties, and uses of the following
Complete and balance the chemical equation:
\[\ce{K2Cr2O7 + H2SO4 + KI →}\] _____ + _____ + _____ + _____.
Chapter: [0.115] Preparation, properties, and uses of the following
| Osmosis and osmotic pressure play a very significant role in biological processes. The osmotic pressure of human blood is 8.21 atm at 27oC. It is interesting to know that a 0.91% (mass/volume) solution of NaCl, known as saline water is isotonic with fluids inside the human red blood cells. In this solution, the blood corpuscles neither swell nor shrink. Therefore, medicines are mixed with saline water before being injected into the veins. |
Answer the following questions.
- What is an isotonic solution?
- How much glucose should be used per 100ml (aqueous solution) for intravenous injection that is isotonic with blood at 27° C?
- What would be the osmotic pressure of blood if the temperature is 37°C?
- A pure NaCl solution with salt concentration less than 0·91% (mass/volume) is hypertonic solution to human blood.
Is this statement true or false? Give a reason. - Name the disease caused by taking a lot of salt or salty food, which results in water retention in tissue cells causing puffiness or swelling.
Chapter: [0.013000000000000001] Relative molecular mass of non-volatile substances
Calculate the boiling point of urea solution when 8.0g of urea is dissolved in 250g of water. Boiling point of pure water is 373K.
(kb of water = 0.52 K kg mol-1, molecular mass of urea = 60 g mol-1)
Chapter: [0.013000000000000001] Relative molecular mass of non-volatile substances
Ethylene glycol is used as an antifreeze agent. Calculate the amount of ethylene glycol to be added to four kilogram of water to prevent it from freezing at −6°C.
(Kf of water = 1.86 K kg mol-1 ) Assume that ethylene glycol (CH2OH.CH2OH) does not dissociate or associate in aqueous solution.
Chapter: [0.013000000000000001] Relative molecular mass of non-volatile substances
What will be the effect on the value of molality and molarity of a solution with change in temperature?
Chapter: [0.015] Normality, molality
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