Chemistry Delhi Set 1 2014-2015 Science (English Medium) Class 12 Question Paper Solution

What is the basicity of H₃PO₄?

Write the IUPAC name of the given compound :

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

Out of BaCl₂ and KCl, which one is more effective in causing coagulation of a negatively charged colloidal Sol? Give reason.

What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy 1/3^rd of tetrahedral voids?

What are the transition elements? Write two characteristics of the transition elements.

Write down the IUPAC name of the following complex: [Cr(NH₃)₂Cl₂(en)]Cl (en = ethylenediamine)

Write the formula for the following complex:

Pentaamminenitrito-O-Cobalt (III)

Name the reagents used in the following reactions:

Name the reagents used in the following reactions:

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

Define azeotropes. 

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

Following reactions occur at cathode during the electrolysis of aqueous silver chloride solution :

`Ag^+(aq)+e^(-)rarrAg(s)" ""      ""       "E^@=+0.80V`

`H^+(aq)+e^(-)rarr1/2H_2(g)" "" "" " E^@=0.00V`

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

Define limiting molar conductivity.

Why conductivity of an electrolyte solution decreases with the decrease in concentration ?

3.9 g of benzoic acid dissolved in 49 g of benzene shows a depression in freezing point of 1.62 K. Calculate the van't Hoff factor and predict the nature of solute (associated or dissociated).

(Given : Molar mass of benzoic acid = 122 g mol⁻¹, K_f for benzene = 4.9 K kg mol⁻¹)

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

What is the role of silica in the extraction of copper?

Which form of the iron is the purest form of commercial iron?

An element with molar mass 27 g mol⁻¹ forms a cubic unit cell with edge length 4.05 ✕ 10⁻⁸ cm. If its density is 2.7 g cm⁻³, what is the nature of the cubic unit cell?

How would you account for the following:

Actinoid contraction is greater than lanthanoid contraction.

How would you account for the following : Transition metals form coloured compounds

Complete the following equation :

`2MnO_4^(-)+6H^++5NO_2^(-)rarr`

Draw the geometrical isomers of complex [Pt(NH₃)₂Cl₂].

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

Write the hybridization and magnetic behaviour of the complex [Ni(CO)₄].

(At.no. of Ni = 28)

Calculate emf of the following cell at 25 °C :

Fe|Fe²⁺(0.001 M)| |H⁺(0.01 M)|H₂(g) (1 bar)|Pt (s)

E°(Fe²⁺| Fe)= −0.44 V E°(H⁺ | H₂) = 0.00 V

Give reasons for the following observations: Leather gets hardened after tanning.

Give reasons for the following observations: Lyophilic sol is more stable than lyophobic sol. 

It is necessary to remove CO when ammonia is prepared by Haber's process.

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

(i) Nylon-6, 6

(ii) PHBV

(iii) Neoprene

Predict the products of the following reactions :

Predict the products of the following reactions :

Predict the products of the following reactions :

How do you convert the following :
Phenol to anisole

How do you convert the following : Propan-2-ol to 2-methylpropan-2-ol

How do you convert the following:

Aniline to phenol

Write the mechanism of the following reaction :

Write the equation involved in the acetylation of Salicylic acid.

Which one of the following is a disaccharide : Starch, Maltose, Fructose, Glucose ?

What is the difference between fibrous protein and globular protein ?

Write the name of vitamin whose deficiency causes bone deformities in children.

Give reasons : n-Butyl bromide has higher boiling point than t-butyl bromide.

Give reasons : Racemic mixture is optically inactive.

The presence of nitro group (−NO₂) at o/p positions increases the reactivity of haloarenes towards nucleophilic substitution reactions.

Mr. Roy, the principal of one reputed school organized a seminar in which he invited parents and principals to discuss the serious issue of diabetes and depression in students. They all resolved this issue by strictly banning the junk food in schools and to introduce 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. Roy 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 :

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

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

(iii) What are tranquillizers ? Give an example.

(iv) Why is use of aspartame limited to cold foods and drinks ?

Account for the following :

Acidic character increases from HF to HI.

Account for the following : There is large difference between the melting and boiling points of oxygen and sulphur.

Account for the following : Nitrogen does not form pentahalide.

Draw the structures of the following : ClF₃

Draw the structures of the following molecules: XeF₄

Which allotrope of phosphorus is more reactive and why?

How the supersonic jet aeroplanes are responsible for the depletion of ozone layers?

F₂ has lower bond dissociation enthalpy than Cl₂. Why?

Which noble gas is used in filling balloons for meteorological observations?

Complete the equation :​ XeF₂+PF₅ →

An aromatic compound 'A' of molecular formula C₇H₇ON undergoes a series of reactions as shown below. Write the structures of A, B, C, D and E in the following reactions :

Write the structures of main products when aniline reacts with the following reagents :

Br₂ water

Write the structures of main products when aniline reacts with the following reagents : HCl

Write the structures of main products when aniline reacts with the following reagents :

(CH₃CO)₂O/pyridine

Arrange the following: C₂H₅NH₂, C₂H₅OH, (CH₃)₃N – in the increasing order of their boiling point

Give a simple chemical test to distinguish between the following pair of compounds :

(CH₃)₂NH and (CH₃)₃N

For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained :

(i) Show that it follows pseudo first order reaction, as the concentration of water remains constant.

(ii) Calculate the average rate of reaction between the time interval 30 to 60 seconds.

(Given log 2 = 0.3010, log 4 = 0.6021)

For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]²

How is the rate of reaction affected if the concentration of B is doubled?

For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]²

What is the overall order of reaction if A is present in large excess?

A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.

(log 2 = 0.3010)