Solution of Chapter 15. Model Test Paper (Chemistry - Exemplar Book)

The pressure-volume work for an ideal gas can be calculated by using the expression;

When hydrochloric acid is added to the cobalt nitrate solution at room temperature, the following reaction takes place :

The solution is blue at room temperature. However, it turns pink when cooled in a freezing mixture. Based on this information, which of the following expression is correct for the forward reaction?

Which of the following elements does not form hydride by direct heating with dihydrogen?

Which of the following species should be aromatic in character?

Identify the pairs which are of isotopes?

Electrophiles are electron seeking species. Which of the following sets consist of electrophiles only.

How many significant figures should be present in the answer of the following calculations?

Complete the following reactions

(i)

(ii)

Give IUPAC name of the compound whose line formula is given below:

Greenhouse effect leads to global warming. Which substances are responsible for the greenhouse effect?

Using molecular orbital theory, compare the bond energy and magnetic character of O₂⁺ and O₂^– species.

Consider the reaction given below :

CaCO₃ (s) → CaO (s) + CO₂ (g)

Predict the effect of increase in temperature on the equilibrium constant of this reaction.

Given that

pH of 0.08 mol dm^–3 HOCl solution is 2.85. Calculate its ionization constant.

Nitric acid is an oxidising agent and reacts with PbO but it does not react with PbO₂. Explain why?

Calculate the strength of 5 volume H₂O₂ solution.

According to de Broglie, matter should exhibit dual behaviour that is both particle and wave like properties. However, a cricket ball of 100g does not move like a wave when it is thrown by a bowler at a speed of 100km/h. Calculate the wavelength of the ball and explain why it does not show wave nature.

Explain why nitrogen has positive electron gain enthalpy whereas oxygen has negative; although first ionisation enthalpy of oxygen is lower than that of nitrogen. Justify your answer.

Write Lewis structure of the following compounds and show formal charge on each atom.

HNO₃, NO₂, H₂SO₄

Although heat is a path function, even then heat absorbed by the system under certain conditions is independent of path. What are those conditions? Explain.

The solubility product of Al(OH)₃ is 2.7 × 10^–11. Calculate its solubility in g L^–1 and also find out pH of this solution. (Atomic mass of Al is 27 u).

Calculate the oxidation number of each sulphur atom in the following compounds:

(a) Na₂S₂O₃ (b) Na₂S₄O₆

Calculate the oxidation number of each sulphur atom in the following compounds:

(a) Na₂S₂O₃ (b) Na₂S₄O₆

(ii) Will the reactivity of both the isotopes of hydrogen be the same towards oxygen? Justify your answer.

(i) Beryllium sulphate and magnesium sulphate are readily soluble in water whereas the sulphates of barium, calcium and strontium are only sparingly soluble. Explain.

(ii) Why is the temperature maintained around 393 K during the preparation of plaster of paris?

Give the reactions involved in the preparation of propane from the following :

(i) CH₃—CH = CH₂

(ii) CH₃ CH₂ CH₂ Cl

(iii) CH₃ CH₂ CH₂ COO^– Na⁺

Assertion (A) : The first ionization enthalpy of alkali metals decreases down the group.

Reason (R) : Increase in number of orbitals increases the shielding effect which outweighs the increasing nuclear charge, therefore, the removal of outermost electron requires less energy on moving down the group.

A. A and R both are correct but R is not the explanation of A.

B. A is false but R is correct.

C. A and R both are correct and R is the correct explanation of A.

D. A and R both are incorrect.

Assertion (A): Nitration of benzene requires the use of concentrated sulphuric acid and nitric acid.

Reason (R): The mixture of acids produces the electrophile for the reaction.

A. A and R both are correct but R is not the explanation of A.

B. A is false but R is correct.

C. A and R both are correct and R is the correct explanation of A.

D. A and R both are incorrect.

Assertion (A) : Ozone is destroyed by solar radiations in upper stratosphere.

Reason (R) : Thinning of ozone layer allows excessive UV radiations to reach the surface of earth.

A. A and R both are correct but R is not the explanation of A.

B. A is false but R is correct.

C. A and R both are correct and R is the correct explanation of A.

D. A and R both are incorrect.

(a) Liquids can be considered as very dense gases. When a liquid phase changes to gas phase, the liquid and the gas phases are in equilibrium and a surface separates the two phases. This surface is visible if both phases are in equilibrium and are below critical tempertaure and pressure. However, it is possible to interconvert liquid and gas wherein two phases are never present together.

With the help of a well-labelled diagram show that CO₂ gas can be liquified by changing the pressure and temperature without passing through the situation when both gaseous and liquid CO₂ are at equilibrium.

(b) Arrange the following liquids in increasing order of their viscosities. Give reason for your answer.

Water, benzene, ethane-1,2-diol.

(a) Explain why :

(i) BCl₃ is a Lewis acid.

(ii) Boric acid is a monobasic acid.

(b) Compound ‘A’ of boron reacts with excess NH₃ to give a compound ‘B’. Compound ‘B’ on heating gives cyclic compound ‘C’. Compound C is called inorganic benzene.

(i) Identify compounds ‘A’, ‘B’ and ‘C’

(ii) Give the reactions involved in these processes.

(a) Write two important differences between inductive and resonance effects.

(b) Give reasons to explain the following observations:

(i) Carbon number ‘2’ in CH₃CH₂Cl has more positive charge than that in CH₃CH₂Br.

(ii) CH₃–CH = CH–CH = CH₂ (I) is more stable than CH₃–CH = CH–CH₂–CH = CH₂ (II).