INTERNATION AL INDIAN SCHOOL,RIYADH

WORKSHEET -11 CHEMISTRY 2019-20

TERM – 3

UNIT -1 SOME BASIC CONCEPTS IN CHEMISTRY

WORKSHEET 1

1.What is the difference between molality and molarity?

2.Calculate the mass percent of calcium, phosphorus and oxygen in calcium

phosphate Ca3(PO4)2.

3. 45.4 L of dinitrogen reacted with 22.7 L of dioxygen and 45.4 L of nitrous

oxide was formed. The reaction is given 2N2(g) + O2(g) ⎯→ 2N2O(g)

Which law is being obeyed in this experiment? Write the statement of the law?

4.Hydrogen gas is prepared in the laboratory by reacting dilute HCl with

granulated zinc. Following reaction takes place. Zn + 2HCl ⎯→ ZnCl 2 + H2

5.Calculate the volume of hydrogen gas liberated at STP when 32.65 g of zinc

reacts with HCl. 1 mol of a gas occupies 22.7 L volume at STP; atomic mass of

Zn = 65.3 u.

6. The density of 3 molal solution of NaOH is 1.110 g mL–1. Calculate the molarity

of the solution.

7. Volume of a solution changes with change in temperature, then, will the molality

of the solution be affected by temperature? Give reason for your answer.

8.The reactant which is entirely consumed in reaction is known as limiting reagent.

In the reaction 2A + 4B → 3C + 4D, when 5 moles of A react with 6 moles of B,

then

(i) which is the limiting reagent?

(ii) calculate the amount of C formed?

UNIT 2. STRUCTURE OF ATOM

1. Arrange s, p and d sub-shells of a shell in the increasing order of effective

nuclear charge (Zeff) experienced by the electron present in them.

2. Show the distribution of electrons in oxygen atom (atomic number 8) using

orbital diagram.

3. Nickel atom can lose two electrons to form Ni2+ ion. The atomic number of

nickel is 28. From which orbital will nickel lose two electrons.

4. Which of the following orbitals are degenerate?

5. Calculate the total number of angular nodes and radial nodes present in 3p

orbital.

6. The arrangement of orbitals on the basis of energy is based upon their (n+l )

value. Lower the value of (n+l ), lower is the energy. For orbitals having same

values of (n+l), the orbital with lower value of n will have lower energy.

I. Based upon the above information, arrange the following orbitals in the

increasing order of energy.

(a) 1s, 2s, 3s, 2p

(b) 4s, 3s, 3p, 4d

(c) 5p, 4d, 5d, 4f, 6s

(d) 5f, 6d, 7s, 7p

II. Based upon the above information, solve the questions given below :

(a) Which of the following orbitals has the lowest energy?

4d, 4f, 5s, 5p

(b) Which of the following orbitals has the highest energy?

5p, 5d, 5f, 6s, 6p

7. The electronic configuration of valence shell of Cu is 3d104s1 and not

3d94s2. How is this configuration explained?

8. Calculate the energy and frequency of the radiation emitted when an electron

jumps from n = 3 to n = 2 in a hydrogen atom.

9. According to de Broglie, matter should exhibit dual behaviour, that is both

particle and wave like properties. However, a cricket ball of mass 100 g does

not move like a wave when it is thrown by a bowler at a speed of 100 km/h.

Calculate the wavelength of the ball and explain why it does not show wave

nature.

10. Which of the following sets of quantum numbers are correct?

UNIT 3. CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

1. Explain why the electron gain enthalpy of fluorine is less negative than that

of chlorine.

2. All transition elements are d-block elements, but all d-block elements are not

transition elements. Explain.

3. Identify the group and valency of the element having atomic number 119. Also

predict the outermost electronic configuration and write the general formula

of its oxide.

4. Ionisation enthalpies of elements of second period are given below :

Ionisation enthalpy/ k cal mol –1 : 520, 899, 801, 1086, 1402, 1314,1681, 2080.

Match the correct enthalpy with the elements and complete the graph given in

Also write symbols of elements with their atomic number.

5. Among the elements B, Al, C and Si,

(i) which element has the highest first ionisation enthalpy?

(ii) which element has the most metallic character?

Justify your answer in each case.

6. Nitrogen has positive electron gain enthalpy whereas oxygen has negative.

However, oxygen has lower ionisation enthalpy than nitrogen. Explain.

7. First member of each group of representative elements (i.e., s and p-block

elements) shows anomalous behaviour. Illustrate with two examples.

8. Arrange the elements N, P, O and S in the order of-

(i) increasing first ionisation enthalpy.

(ii) increasing non metallic character.

Give reason for the arrangement assigned.

1. Explain the deviation in ionisation enthalpy of some elements from the

general trend by using the below fig.

UNIT-4 CHEMICAL BONDING AND MOLECULAR STRUCTURE

1. Explain the non linear shape of H2S and non planar shape of PCl3 using valence

shell electron pair repulsion theory.

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

and O2–species.

3. Explain the shape of BrF5

4. Structures of molecules of two compounds are given below :

(a) Which of the two compounds will have intermolecular hydrogen bonding

and which compound is expected to show intramolecular hydrogen

bonding.

(b) The melting point of a compound depends on, among other things, the

extent of hydrogen bonding. On this basis explain which of the above

two compounds will show higher melting point.

(c) Solubility of compounds in water depends on power to form hydrogen

bonds with water. Which of the above

4. Explain why PCl5 is trigonal bipyramidal whereas IF5 is square pyramidal.

5. Write Lewis structure of the following compounds and show formal charge

on each atom HNO3 and H2SO4

6. Give reasons for the following :

(i) Covalent bonds are directional bonds while ionic bonds are non-directional.

(ii) Water molecule has bent structure whereas carbon dioxide molecule is linear.

(iii) Ethyne molecule is linear.

7. Explain why CO32– ion cannot be represented by a single Lewis structure. How can it

be best represented?

8. Predict the hybridisation of each carbon in the molecule of organic compound

given below. Also indicate the total number of sigma and pi bonds in this

molecule.

9. Elements X, Y and Z have 4, 5 and 7 valence electrons respectively. (i) Write

the molecular formula of the compounds formed by these elements individually

with hydrogen. (ii) Which of these compounds will have the highest dipole

moment?

UNIT – 5 STATES OF MATTER

1. Two different gases ‘A’ and ‘B’ are filled in separate containers of equal capacity

under the same conditions of temperature and pressure. On increasing the

pressure slightly the gas ‘A’ liquefies but gas B does not liquify even on applying

high pressure until it is cooled. Explain this phenomenon.

2. Value of universal gas constant (R) is same for all gases. What is its physical

significance?

3. One of the assumptions of kinetic theory of gases states that “there is no force

of attraction between the molecules of a gas.” How far is this statement correct?

Is it possible to liquefy an ideal gas? Explain.

4. what are the factors on which surface tension and viscosity depends on ?

5. Compressibility factor, Z, of a gas is given as pV= ZnRT

(i) What is the value of Z for an ideal gas?

(ii) For real gas what will be the effect on value of Z above Boyle’s temperature?

6. The critical temperature (Tc) and critical pressure ( pc) of CO2 are 30.98°C and

73 atm respectively. Can CO2 ( g) be liquefied at 32°C and 80 atm pressure?

7. Name two phenomena that can be explained on the basis of surface tension.

8. Viscosity of a liquid arises due to strong intermolecular forces existing between

the molecules. Stronger the intermolecular forces, greater is the viscosity.

Name the intermolecular forces existing in the following liquids and arrange

them in the increasing order of their viscosities. Also give reason for the

assigned order in one line.

Water, hexane (CH3CH2CH2CH2CH2CH3), glycerine (CH2OH CH(OH) CH2OH)

9. Explain the effect of increasing the temperature of a liquid, on intermolecular

forces operating between its particles, what will happen to the viscosity of a

liquid if its temperature is increased?

10 . Pressure versus volume graph

for a real gas and an ideal gas

are shown in Fig. 5.4. Answer the following questions on the basis of this graph.

(i) Interpret the behaviour of real gas with respect to ideal gas at low pressure.

(ii) Interpret the behaviour of real gas with respect to ideal gas at high pressure.

(iii) Mark the pressure and

volume by drawing a

line at the point where real gas behaves as an

ideal gas.

States of matter-solid state

UNIT 7. REDOX REACTIONS

1. MnO4 undergoes disproportionation reaction in acidic medium but MnO4–

does not. Give reason.

2. Nitric acid is an oxidising agent and reacts with PbO but it does not react

with PbO2. Explain why?

3. Write balanced chemical equation for the following reactions:

(i) Permanganate ion (MnO4– ) reacts with sulphur dioxide gas in acidic

medium to produce Mn2+ and hydrogen sulphate ion.

(Balance by ion electron method)

(ii) Reaction of liquid hydrazine (N2H4) with chlorate ion (ClO3–) in basic

medium produces nitric oxide gas and chloride ion in gaseous state.

(Balance by ion electron method)

(iii) Dichlorine heptaoxide (Cl2O7) in gaseous state combines with an

aqueous

solution of hydrogen peroxide in acidic medium to give chlorite ion

(ClO2–) and oxygen gas.

(Balance by ion electron method)

4. Calculate the oxidation number of each sulphur atom in the following

compounds:

10.THE s- BLOCK ELEMENTS

1. How do you account for the strong reducing power of lithium in aqueous

solution?

2. Why do beryllium and magnesium not impart colour to the flame in the

flame test ?

3. All compounds of alkali metals are easily soluble in water but lithium

compounds are more soluble in organic solvents. Explain.

4.In the Solvay process, can we obtain sodium carbonate directly by

treating the solution containing ammonium carbonate with sodium

chloride? Explain.

5. Discuss the trend of the following:

(i) Thermal stability of carbonates of Group 2 elements.

(ii) The solubility and the nature of oxides of Group 2 elements.

6.Name an element from Group 2 which forms an amphoteric oxide and a

water Soluble sulphate.

7.Why are BeSO4 and MgSO4readily soluble in water while CaSO4, SrSO4 and

BaSO4 are insoluble?

UNIT 12 ORGANIC CHEMISTRY SOME BASIC PRINCIPLES AND TECHNIQUES

Consider structures I to VII and answer the questions 1 to 4

1. Which of the above compounds form pairs of metamers?

2. Identify the pairs of compounds which are functional group isomers.

3. Identify the pairs of compounds that represents position isomerism.

4. Identify the pairs of compounds that represents chain isomerism.

5. For testing halogens in an organic compound with AgNO3 solution,

sodium extract (Lassaigne’s test) is acidified with dilute HNO3. What will

happen if a student acidifies the extract with dilute H2SO4 in place of dilute

HNO3?

4. What is the hybridisation of each carbon in H2C = C = CH2.

5. Explain, how is the electronegativity of carbon atoms related to their state of

hybridisation in an organic compound?

6. Show the polarisation of carbon-magnesium bond in the following structure.

CH3—CH2—CH2—CH2—Mg—X

7. Compounds with same molecular formula but differing in their structures are

said to be structural isomers. What type of structural isomerism is shown by

8. If a liquid compound decomposes at its boiling point, which method (s) can

you choose for its purification. It is known that the compound is stable at

low

pressure, steam volatile and insoluble in water.

UNIT 13 HYDROCARBONS

1. Why do alkenes prefer to undergo electrophilic addition reaction while arenes

prefer electrophilic substitution reactions? Explain.

2. Alkynes on reduction with sodium in liquid ammonia form trans alkenes.

Will the butene thus formed on reduction of 2-butyne show the geometrical

isomerism?

3. Rotation around carbon-carbon single bond of ethane is not completely free.

Justify the statement.

4. Draw Newman and Sawhorse projections for the eclipsed and staggered

conformations of ethane. Which of these conformations is more stable and why?

5. 28. Despite their - I effect, halogens are o- and p-directing in haloarenes. Explain.

6. 29. Why does presence of a nitro group make the benzene ring less reactive in

7. comparison to the unsubstituted benzene ring. Explain.

8. 30. Suggest a route for the preparation of nitrobenzene starting from acetylene?

9. Which of the following compounds are aromatic according to Huckel’s rule?

UNIT-6 THERMODYNAMICS

1. 18.0 g of water completely vapourises at 100°C and 1 bar pressure and the enthalpy

change in the process is 40.79 kJ mol –1. What will be the enthalpy change for

vapourising two moles of water under the same conditions? What is the standard

enthalphy of vapourisation for water?

2. One mole of acetone requires less heat to vapourise than 1 mol of water. Which of

the two liquids has higher enthalpy of vapourisation?

3. Standard molar enthalpy of formation, ΔfH is just a special case of enthalpy of

reaction, Δr H

Is the ΔrH for the following reaction same as Δf H? Give reason for your answer.

CaO(s) + CO2(g) → CaCO3(s); ΔfH = –178.3 kJ mol–1

4. Given that ΔH= 0 for mixing of two gases. Explain whether the diffusion of these

gases into each other in a closed container is a spontaneous process or not?

5. Increase in enthalpy of the surroundings is equal to decrease in enthalpy of

the system. Will the temperature of system and surroundings be the same

when they are in thermal equilibrium?

UNIT 7- EQUILIBRIUM

1. The ionisation of hydrochloric in water is given below:

Label two conjugate acid-base pairs in this ionisation.

2. BF3 does not have proton but still acts as an acid and reacts with NH3. Why is

it so? What type of bond is formed between the two?

3. The value of Kc for the reaction At a given time, the

composition of reaction mixture is

In which direction will the reaction proceed?

4. pH of a solution of a strong acid is 5.0. What will be the pH of the solution

obtained after diluting the given solution a 100 times?

5. Conjugate acid of a weak base is always stronger. What will be the decreasing

order of basic strength of the following conjugate bases?

9.HYDROGEN

1. How can production of hydrogen from water gas be increased by using

water

gas shift reaction?

2. What are metallic/interstitial hydrides? How do they differ from

molecular

hydrides?

3. Name the classes of hydrides to which H2O, B2H6 and NaH belong.

Complete the following equations:

4. What do you understand by the term ‘auto protolysis of water’ ? What is

its

significance?

5. Write one chemical reaction for the preparation of D2O2.

6. Calculate the strength of 5 volume H2O2 solution.

11. THE p -BLOCK ELEMENTS

1. The +1 oxidation state in group 13 and +2 oxidation state in group 14

becomes more and more stable with increasing atomic number. Explain.

2. Explain the following:

(i) Gallium has higher ionisation enthalpy than aluminium.

(ii) Boron does not exist as B3+ ion.

(iii) Aluminium forms [AlF6]3– ion but boron does not form [BF6]3– ion.

(iv) PbX2 is more stable than PbX4.

(v) Pb4+ acts as an oxidising agent but Sn2+ acts as a reducing agent.

(vi) Electron gain enthalpy of chlorine is more negative as compared to

flurine

(vii) Tl (NO3)3 acts as an oxidising agent.

(viii) Carbon shows catenation property but lead does not.

(ix) BF3does not hydrolyse.

(x) Why does the element silicon, not form a graphite like structure while

Carbon does.

3. Identify the compounds A, X and Z in the following reactions :

4. Complete the following chemical equations

5. When BCl3 is treated with water, it hydrolyses and forms [B[OH]4]– only

whereas AlCl3 in acidified aqueous solution forms [Al (H2O) 6]3+ ion. Explain

what is the hybridisation of boron and aluminium in these species?

UNIT-14 ENVIRONMENTAL CHEMISTRY

1. Green house effect leads to global warming. Which substances are responsible

for green house effect?

2. Acid rain is known to contain some acids. Name these acids and where from

they come in rain?

3. Ozone is a toxic gas and is a strong oxidising agent even then its presence in

the stratosphere is very important. Explain what would happen if ozone from

this region is completely removed?

4. Dissolved oxygen in water is very important for aquatic life. What processes

are responsible for the reduction of dissolved oxygen in water?

5. On the basis of chemical reactions involved, explain how do

chlorofluorocarbons cause thinning of ozone layer in stratosphere.

6. What could be the harmful effects of improper management of industrial and

domestic solid waste in a city?