Chemistry Foreign Set 2 2014-2015 Science (English Medium) Class 12 Question Paper Solution

What is the formula of a compound in which the element Y forms hcp lattice and atoms of X occupy 2/3^rd of tetrahedral voids?

Write the IUPAC name of the given compound :

Physisorption is reversible while chemisorption is irreversible. Why ?

Which would undergo S_N2 reaction faster in the following pair and why ?

CH₃ – CH₂ ​– Br and CH₃ ​– CH₂ ​– I

Which allotrope of sulphur is thermally stable at room temperature ?

 Following reactions occur at cathode during the electrolysis of aqueous copper(II) chloride solution :

On the basis of their standard reduction electrode potential (E°) values, which reaction is feasible at the cathode and why ?

State Kohlrausch law of independent migration of ions. 

Why do transition elements show variable oxidation states ? In 3d series (Sc to Zn), which elements shows the maximum number of oxidation state and why ?

Write down the IUPAC name of the following complex :

[Cr(en)₃]Cl₃

Using IUPAC norms, write the formula for the following:

Potassium tetrachloridopalladate(II)

Name the reagents used in the following reactions:

Name the reagents used in the following reactions:

What is meant by negative deviation from Raoult's law? Give an example. What is the sign of ∆_mixH for negative deviation?

Define azeotropes. 

What type of azeotrope is formed by positive deviation from Raoult's law ? Give an example.

Why are alkyl halides insoluble in water?

Why is Butan-1-ol optically inactive but Butan-2-ol is optically active?

Although chlorine is an electron withdrawing group, yet it is ortho-, para- directing in electrophilic aromatic substitution reactions. Why?

How will you bring about the following conversion in not more than two steps?

Benzoic acid to Benzaldehyde

How do you convert the following :

 Ethyne to Ethanal

How do you convert the following :

Acetic acid to Methane

Write the equations involved in the following reactions :

Stephen reaction

Write the equations involved in the following reactions :

Wolff-Kishner reduction

Write the equations involved in the following reactions :

Etard reaction

Calculate the mass of NaCl (molar mass = 58.5 g mol⁻¹) to be dissolved in 37.2 g of water to lower the freezing point by 2°C, assuming that NaCl undergoes complete dissociation. (K_f for water = 1.86 K kg mol⁻¹)

Write the names and structures of the monomers of the following polymers:

(i) Terylene
(ii) Bakelite
(iii) Buna-S

Which one of the following is a monosaccharide: 

 starch, maltose, fructose, cellulose

What is the difference between acidic amino acids and basic amino acids?

 Write the name of the vitamin whose deficiency causes bleeding of gums.

Draw the geometrical isomers of complex \[\ce{[Pt(en)2Cl2]^2+}\].

On the basis of crystal field theory, write the electronic configuration for d⁴ ion if ∆₀ < P.

Write the hybridization type and magnetic behaviour of the complex [Ni(CN)₄]²⁻. (Atomic number of Ni = 28)

Indicate the principle behind the method used for the refining of Nickel.

What is the role of dilute NaCN in the extraction of gold ?

What is 'copper matte' ?

Calculate the emf of the following cell at 25°C :

Predict the products of the following reactions :

Predict the products of the following reactions :

An element X (molar mass = 60 g mol⁻¹) has a density of 6.23 g cm⁻³. Identify the type of cubic unit cell, if the edge length of the unit cell is 4 ✕ 10⁻⁸ cm.

How would you account the following :

Highest fluoride of Mn is MnF₄ whereas the highest oxide is Mn₂O₇.

 How would you account the following :

 Transition metals and their compounds show catalytic properties.

Complete the following equation :

Give reasons for the following observations :

 A delta is formed at the meeting point of sea water and river water.

Give reasons for the following observations :

NH₃ gas adsorbs more readily than N₂ gas on the surface of charcoal.

Give reasons for the following observations :

 Powdered substances are more effective  adsorbents.

Seeing the growing cases of diabetes and depression among children, Mr. Chopra, the principal of one reputed school organized a seminar in which he invited parents and principals. They all resolved this issue by strictly banning the junk food in schools and by introducing healthy snacks and drinks like soup, lassi, milk etc. in school canteens. They also decided to make compulsory half an hour physical activities for the students in the morning assembly daily. After six months, Mr. Chopra conducted the health survey in most of the schools and discovered a tremendous improvement in the health of students.

After reading the above passage, answer the following questions :

(i) What are the values (at least two) displayed by Mr. Chopra ?

(ii) As a student, how can you spread awareness about this issue ?

(iii) Why should antidepressant drugs not be taken without consulting a doctor ?

(iv) Give two examples of artificial sweeteners.

Illustrate the following reactions giving suitable example in each case 

Ammonolysis

Illustrate the following reactions giving suitable example in each case 

Coupling reaction

Illustrate the following reactions giving suitable example in each case 

Acetylation of amines

 Describe Hinsberg method for the identification of primary, secondary and tertiary amines. Also write the chemical equations of the reactions involved.

Write the structures of main products when benzene diazonium chloride (C6 H5 N+2CI−)C6 H5 N2+CI- reacts with the  :  HBF₄/∆

 Write the structures of main products when benzene diazonium chloride (C6 H5 N+2CI−)C6 H5 N2+CI- reacts with the :Cu/HBr

Write the structures of A, B and C in the following reactions :

\[ C_6 H_5 {NO}_2 \to^{Sn/HCI} A \to^{{NaNO}_2 /HCI}_{273 K} B \to^{H_2 O}_∆ C\]

Write the structures of A, B and C in the following reactions :

Define activation energy.

Define the following terms: Rate constant

A first order reaction takes 10 minutes for 25% decomposition. Calculate t_1/2 for the reaction.

(Given : log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021)

For a chemical reaction R → P, the variation in the concentration (R) vs. time (t) plot is given as:

(i) Predict the order of the reaction.

(ii) What is the slope of the curve ?

(iii) Write the unit of rate constant for this reaction.

Show that the time required for 99% completion is double of the time required for the completion of 90% reaction.

Account for the following :

Bond angle in NH+4NH4+ is higher than NH₃.

Account for the following :

H₂S has lower boiling point than H₂O.

Account for the following :

Reducing character decreases from SO2 to TeO₂.

Draw the structures of the following: H₄P₂O₇ (Pyrophosphoric acid)

Draw the structures of the following molecules: XeF₂

Draw the structures of the following molecules: XeF₄

Draw the structures of the following :

H₂S2O₇

Account for the following :

Iron on reaction with HCl forms FeCl₂ nd not FeCl₃.

Account for the following :

HClO₄ is a stronger acid than HClO.

Account for the following :

BiH₃ is the strongest reducing agent amongst all the hydrides of group 15.