Chemistry Delhi Set 1 2017-2018 Science (English Medium) Class 12 Question Paper Solution

An analysis shows that FeO has a non-stoichiometric composition with formula Fe_0.95O. Give reason.

CO (g) and H₂ (g) react to give different products in the presence of different catalysts. Which ability of the catalyst is shown by these reactions?

Write the coordination number and oxidation state of Platinum in the complex [Pt(en)₂Cl₂].

Out of chlorobenzene and benzyl chloride, which one gets easily hydrolysed by aqueous NaOH and why?

Write the IUPAC name of the following :

Calculate the freezing point of a solution containing 60 g of glucose (Molar mass = 180 g mol^–1) in 250 g of water. (K_f of water = 1.86 K kg mol^–1)

For the reaction 

2N₂O₅ (g) → 4NO₂ (g) + O₂ (g), the rate of formation of NO₂ (g) is 2·8 × 10^–3 M s^–1. Calculate the rate of disappearance of N₂O₅ (g).

Among the hydrides of Group-15 elements, which have the lowest boiling point?

Among the hydrides of Group-15 elements, which have the maximum basic character?

Among the hydrides of Group-15 elements, which have the highest bond angle?

Among the hydrides of Group-15 elements, which have the maximum reducing character?

How do you convert the Ethanal to Propanone

How do you convert the Toluene to Benzoic acid

Account for the following:

Aromatic carboxylic acids do not undergo Friedel-Crafts reaction.

Account for the following:

pK_a value of 4-nitrobenzoic acid is lower than that of benzoic acid.

Complete and balance the following chemical equations

`Fe^(2+) + MnO_4^(-) + H^+ ->`

Complete and balance the following chemical equations

`MnO_4^(-) + H_2O + I^(-) ->`

Give reasons for the following:

Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers.

Give reasons for the following :

Aquatic animals are more comfortable in the cold water than in warm water.

Give reasons for the following

Elevation of the boiling point of 1 M KCl solution is nearly double than that of 1 M sugar solution.

An element 'X' (At. mass = 40 g mol^-1) having f.c.c. the structure has unit cell edge length of 400 pm. Calculate the density of 'X' and the number of unit cells in 4 g of 'X'. (N_A = 6.022 × 10²³ mol^-1)

A first-order reaction is 50% completed in 40 minutes at 300 K and in 20 minutes at 320 K. Calculate the activation energy of the reaction. (Given : log 2 = 0·3010, log 4 = 0·6021, R = 8·314 JK^–1 mol^–1)

What happens when a freshly prepared precipitate of Fe(OH)₃ is shaken with a small amount of FeCl₃ solution?

What happens when persistent dialysis of a colloidal solution is carried out?

What happens when an emulsion is centrifuged?

Write the chemical reactions involved in the process of extraction of Gold. Explain the role of dilute NaCN and Zn in this process.

Give reasons: E° value for the Mn³⁺/Mn²⁺ couple is much more positive than that for Fe³⁺/Fe²⁺.

Give reasons Iron has the higher enthalpy of atomization than that of copper.

Give reasons: Sc³⁺ is colourless in aqueous solution whereas Ti³⁺ is coloured.

Identify the chiral molecule in the following pair :

Write the structure of the product when chlorobenzene is treated with methyl chloride in the presence of sodium metal and dry ether.

Write the structure of the alkene formed by dehydrohalogenation of 1-Bromo-1methylcyclohexane with alcoholic KOH.

(A), (B) and (C) are three non-cyclic functional isomers of a carbonyl compound with molecular formula C₄H₈O. Isomers (A) and (C) give positive Tollens' test whereas isomer (B) does not give Tollens' test but gives positive Iodoform test. Isomers (A) and (B) on reduction with Zn(Hg)/conc. HCl give the same product (D).

1) Write the structures of (A), (B), (C) and (D).

2) Out of (A), (B), and (C) isomers, which one is least reactive towards the addition of HCN?

Write the structures of the main products in the following reactions :

Write the structures of the main products in the following reactions :

Write the structures of the main products in the following reactions :

Why is bithional added to soap?

What is tincture of iodine? What is its use?

Among the following, which one acts as a food preservative?

Aspartame, Aspirin, Sodium Benzoate, Paracetamol

Define the following with an example of each

Polysaccharides

Define the following with an example

Denatured protein

Define the following terms: Essential amino acids

Write the product when D-glucose reacts with conc. HNO₃.

Amino acids show amphoteric behaviour. Why?

Write one difference between α-helix and β-pleated structures of proteins.

Write the formulas for the following coordination compounds:

Iron(III) hexacyanoferrate(II)

What type of isomerism is exhibited by the complex `[Co(NH_3)_5Cl]SO_4`?

Write the hybridisation and number of unpaired electrons in the complex `[CoF_6]^(3-)`. (Atomic No. of Co = 27)

Shyam went to a grocery shop to purchase some food items. The shopkeeper packed all the items in polythene bags and gave them to Shyam. But Shyam refused to accept the polythene bags and asked the shopkeeper to pack the items in paper bags. He informed the shopkeeper about the heavy penalty imposed by the government for using polythene bags. The shopkeeper promised that he would use paper bags in future in place of polythene bags.

1) Write the values (at least two) shown by Shyam.

2) Write one structural difference between low-density polyethene and high-density polyethene.

3) Why did Shyam refuse to accept the items in polythene bags?

4) What is a biodegradable polymer? Give an example.

Give reasons H₃PO₃ undergoes disproportionation reaction but H₃PO₄ does not.

Give reasons When Cl₂ reacts with the excess of F₂, ClF₃ is formed and not FCl₃.

Give reasons Dioxygen is a gas while Sulphur is a solid at room temperature.

Draw the structures of the following molecules: XeF₄

Draw the structures of the HClO₃.

When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas (A) was evolved. This gas intensified when copper turnings were added to this test tube. On cooling, the gas (A) changed into a colourless solid (B).

1) Identify (A) and (B).

2) Write the structures of (A) and (B).

3) Why does gas (A) change to solid on cooling?

Arrange the following in the decreasing order of their reducing character :

HF, HCl, HBr, HI

What happens when: XeF₄ reacts with SbF₅?

Write the cell reaction and calculate the e.m.f of the following cell at 298 K:

`Sn(s) | Sn^(2+) (0.004 M) || H^(+) (0.020 M) | H_2 (g) ("1 bar") | Pt(s)`

(Given: `E_(Sn^(2+)"/"Sn)^0 = -0.14` V)

Give reasons On the basis of E° values, O₂ gas should be liberated at anode but it is Cl₂ gas which is liberated in the electrolysis of aqueous NaCl.

Give reasons Conductivity of CH₃COOH decreases on dilution.

For the reaction

`2AgCl (s) + H_2 (g) ("1 atm") -> 2Ag (s) + 2H^(+)  (0.1 M) +  2Cl^(-) (0.1 M)`

`triangleG^0 = -43600 J at 25^@ C`

Calculate the e.m.f. of the cell

`[log 10^(-n) = -n]` 

Define terms: Fuel cell

Write two advantages of fuel cell

Write the chemical equations involved in the following reactions:(i) Hoffmann-bromamide degradation reaction

Illustrate the following reaction giving suitable example in each case: Diazotisation

Illustrate the following reaction giving suitable example in each case:Gabriel phthalimide synthesis

Give reason (CH₃)₂NH is more basic than (CH₃)₃N in an aqueous solution.

Give reason Aromatic diazonium salts are more stable than aliphatic diazonium salts.

Write the structures of the main products of the following reactions:

Write the structures of the main products of the following reactions:

Write the structures of the main products of the following reactions:

Give a simple chemical test to distinguish between Aniline and N, N-dimethylaniline

Arrange the following in the increasing order of their pK_b values:

C₆H₅NH₂, C₂H₅NH₂, C₆H₅NHCH₃