MODEL PAPER 1 Chemistry - MODEL PAPER 1

Which of the following methods of preparation of amines will give same number of carbon atoms in the chain of amines as in the reactant?

The conversion of an alkyl halide into alcohol by aqueous NaOH is classified as

Which one of the following compounds is more reactive towards S_N1 reaction?

Assertion (A): RCHO, RCOCH₃ and cyclic ketones react with sodium bisulphite.
Reason (R): Crystalline solid derivatives are formed when aldehydes or ketones are shaken with saturated aqueous solution of sodium bisulphite.

Assertion (A): Primary structure of proteins gives an idea about the conformation of the molecule.
Reason (R): The differences in chemical and biological properties of various proteins arise due to the difference in primary structure.

Assertion (A): Last traces of moisture in ethanol can be removed by keeping it over sodium wire
Reason (R): Sodium reacts with water but not with ethanol to produce H₂ gas.

Assertion (A): Aryl halide gives a mixture of o- and p-products.
Reason (R): Aryl halides undergo electrophilic substitutions more readily than benzene.

The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non-volatile, non-electrolyte solid weighing 0.5 g when added to 39.0 g of benzene (molar mass 78 g mol_{-1). Vapour pressure of the solution, then, is 0.845 bar. What is the molar mass of the solid substance?}

Answer the following:
(a) For a certain reaction large fraction of molecules has energy more than the threshold energy, yet the rate of reaction is very slow. Why?
(b) State a condition under which a bimolecular reaction is kinetically first-order reaction.

Describe how the following conversions can be brought about (any two)?
i. Cyclohexanol to cyclohexan-1-one.
ii. Ethyl benzene to benzoic acid.
iii. Bromobenzene to benzoic acid.

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL of water at 37°C.

What is lanthanoid contraction? What is its effect on the chemistry of the elements which follow the lanthanoids?

Give the major products that are formed by heating each of the following ethers with HI.

Consider a certain reaction A → Products with k = 2.0 × 10^-2 s^-1. Calculate the concentration of A remaining after 100 s if the initial concentration of A is 1.0 mol L^-1.

What is an electrochemical series? How does it help in calculating the e.m.f of a standard cell?

One of the two figures given below represents substitution and the other represents elimination. Indicate which is substitution and which is elimination.

Attempt any five of the following:
(a) What is the structural feature characterising reducing sugars?
(b) What type of linkage is present in polysaccharides?
(c) Give examples of fat soluble vitamins.
(d) The two strands in DNA are not identical but are complementary. Explain.
(e) Write uses of B-Complex.
(f) Name the disaccharide which on hydrolysis gives two molecules of glucose.
(g) Name purines present in DNA?

(i). Illustrate the following reactions giving suitable example in each case:
a. Ammonolysis
b. Coupling reaction
c. Acetylation of amines
(ii). Describe Hinsberg method for the identification of primary, secondary and tertiary amines. Also, write the chemical equations of the reactions involved.

Using Valence bond theory, explain the following in relation to the paramagnetic complex [Mn(CN)₆]^3-
a. type of hybridisation
b. magnetic moment value
c. type of complex - inner, outer orbital complex

Read the following text carefully and answer the questions that follow:
Aariv Sharma is very fond of a special drink made by his grandmother using different fruits available in their hometown. It has an outstanding taste and also provide great health benefits of natural fruits. He thought of utilizing his grandmother recipe to create a new product in the beverage market that provide health benefits and also contain fizziness of various soft drinks available in the market.
i. How he can add fizz to the special drink made by his grandmother? (1)
ii. What is the law stated in the chapter that can help Aariv to make his drink fizzy? (1)
iii. What precautions he should take while bottling so that his product does not lose fizz during storage and handling across long distances? (2)

Read the following text carefully and answer the questions that follow:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since delectron bonding levels are involved, the cations-exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
i. Why does copper, which is in first series of transition metal exhibits +1 oxidation state most frequently? (1)
ii. The lowest oxide of transition metal is basic. Why? (1)
iii. The variability in oxidation states of d-block different from that of the p-block elements. Explain. (2)

Crystal structure of oxides of transition metals often show defects. Given reason. (2)

The mole fraction of helium in a saturated solution at 20°C is 1.2 g 10-6. Find the pressure of helium above the solution. Given Henry's constant at 20°C is 144.97 kbar. (2)