Model Paper 2

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Questions:

Multiple Choice Question

10 x 1 = 10

Assertion: Permanent hardness of water is removed by treatment with washing soda.
Reason: Washing soda reacts with soluble calcium and magnesium chlorides and sulphates in hard water to form insoluble carbonates

(a)

Both assertion and reason are true and reason is the correct explanation of assertion.

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

Assertion is true but reason is false

(d)

Both assertion and reason are false

Lithium shows diagonal relationship with _____________

(a)

sodium

(b)

magnesium

(c)

calcium

(d)

aluminium

Find the wrong statement

(a)

sodium metal is used in organic qualitative analysis

(b)

sodium carbonate is soluble in water and it is used in inorganic qualitative analysis

(c)

potassium carbonate can be prepared by solvay process

(d)

potassium bicarbonate is acidic salt

In solid ice, oxygen atom is surrounded _____________

(a)

tetrahedrally by 4 hydrogen atoms

(b)

octahedrally by 2 oxygen and 4 hydrogen atoms

(c)

tetrahedrally by 2 hydrogen and 2 oxygen atoms

(d)

octahedrally by 6 hydrogen atoms

The reaction H₃PO₂ + D₂O ➝ H₂DPO₂ + HDO indicates that hypo-phosphorus acid is _____________

(a)

tribasic acid

(b)

dibasic acid

(c)

mono basic acid

(d)

none of these

A commercial sample of hydrogen peroxide marked as 100 volume H₂O₂, it means that _____________

(a)

1 ml of H₂O₂ will give 100 ml O₂ at STP

(b)

1 L of H₂O₂ will give 100 ml O₂ at STP

(c)

1 L of H₂O₂ will give 22.4 L O₂

(d)

1 ml of H₂O₂ will give 1 mole of O₂ at STP

Zeolite used to soften hardness of water is hydrated _____________

(a)

Sodium aluminium silicate

(b)

Calcium aluminium silicate

(c)

Zinc aluminium borate

(d)

Lithium aluminium hydride

The cause of permanent hardness of water is due to _____________

(a)

Ca(HCO₃)₂

(b)

Mg(HCO₃)₂

(c)

CaCl₂

(d)

MgCO₃

Water gas is _____.

(a)

H₂O_(g)

(b)

CO + H₂O

(c)

CO + H₂

(d)

CO + N₂

10.

Which of the following statements about hydrogen is incorrect?

(a)

Hydrogen ion, H₃O⁺ exists freely in solution.

(b)

Dihydrogen acts as a reducing agent.

(c)

Hydrogen has three isotopes of which tritium is the most common.

(d)

Hydrogen never acts as cation in ionic salts.

Generic 3

2 x 3 = 6

11.

Give the uses of gypsum.

12.

How is plaster of paris prepared ?

Generic 5

10 x 5 = 50

13.

When the first element of the periodic table is treated with dioxygen, it gives a compound whose solid state floats on its liquid state. This compound has an ability to act as an acid as well as a base. What products will be formed when this compound undergoes autoionisation ?

14.

Dihydrogen reacts with dioxygen (O₂) to form water. Write the name and formula of the product when the isotope of hydrogen which has one proton and one neutron in its nucleus is treated with oxygen. Will the reactivity of both the isotopes be the same towards oxygen? Justify your answer.

15.

An element (A) which is used in metallurgy for the reduction of metal oxide to metal reacts with carbon monoxide and forms an industrial solvent (B). The industrially produced element (A) reacts with nitrogen to form compound (C). Identify A, B, and C.

16.

Compound A is an important peroxide which disproportionates to give oxygen and water. Compound A reacts with ferrous sulphate under the acidic condition to give compound B. Compound A reacts with KMnO₄ in basic condition to form (C) and (D) along with water and CO₂ What are A, B, C and D ? Write down the equations involved in their formation.

17.

Identify the compound (A) which is a universal solvent. Compound A reacts with chlorine gas to give B and C. Compound A dissolves in an ionic compound of silicon to give compound D. Identify A and write the equations involved in the formation of B, C, and D.

18.

An element (A) belonging to group number 1 and period number 3 react with dihydrogen to form anhydride (B). The element (A) reacts with the universal solvent to give a strong base (C). Identify A, B, and C.

19.

Difference between ortho and para hydrogen

20.

Discuss the uses of hydrogen.

21.

Illustrate the industrial applications of hydrogen depending on
(i) The heat liberated when its atoms are made to combine on the surface of metal.
(ii) Its effect on unsaturated organic system.
(iii) Its ability to combine with nitrogen under specific conditions.

22.

Compare the structures of H₂O and H₂O₂ .

Generic 2

8 x 2 = 16

23.

What is Heavy water?

24.

What causes hardness in water?

25.

Explain the reaction of water with halogens.

26.

What happens when steam is passed over hot iron.

27.

Complete the following reactions and balance them:
(i) CO_(g)+ H_2(g)➝
(ii) CH_4(g)+ H₂O_(g)\(\overset { 1270K }{ \underset { Ni }{ \rightarrow } } \)

28.

What are the advantages of using hydrogen as fuel?

29.

What is Hydrogenation?

30.

Write a note on Haber's process.

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Answers Key:

Multiple Choice Question

10 x 1 = 10

(a)
Both assertion and reason are true and reason is the correct explanation of assertion.

(b)
magnesium

(a)
tetrahedrally by 4 hydrogen atoms

(a)
1 ml of H₂O₂ will give 100 ml O₂ at STP

(a)
Sodium aluminium silicate

10.

Generic 3

2 x 3 = 6

11.

1. Gypsum is used in making drywalls or plaster boards.
2. Another important use of gypsum is the production of plaster of Paris. Gypsum is heated to about 300 degree Fahrenheit to produce plaster of paris, which is also known as gypsum plaster. It is mainly used as a sculpting material.
3. Gypsum is used in making surgical and orthopedic casts, such as surgical splints and casting moulds.
4. Gypsum plays an important role in agriculture as a soil additive, conditioner, and fertilizer. It helps loosen up compact or clay soil, and provides calcium and sulphur, which are essential for the healthy growth of a plant.
5. Gypsum is used in toothpastes, shampoos, and hair products.
6. Gypsum is a component of portland cement, where it acts as a hardening retarder to control the speed at which concrete sets.

12.

Calcium Sulphate (plaster of paris), CaSO₄. 1/2H₂O :
It is a hemihydrate of calcium sulphate. It is obtained when gypsum, CaSO₄.2H₂O,is heated to 393 K
2(CaSO₄.2H₂O) ⟶ 2CaSO₄,H₂O + 3H₂O
Above 393 K, no water of crystallisation is left and anhydrous calcium sulphate, CaSO₄ is formed. This is a known 'dead burnt plaster'.
It has a remarkable property of setting with water. on mixing with an adequate quantity of water it forms a plastic mass that gets into hard solid in 5 to 15 minutes.

Generic 5

10 x 5 = 50

13.

The first element of the periodic table is hydrogen.
2H₂+ O₂ ➝ 2H₂O
The compound formed is water.
Auto - ionization or auto-protolysis of water proceeds as follows
\(\underset { Acid }{ { H }_{ 2 }O(l) } +\underset { Base }{ { H }_{ 2 }O(l) } \longleftrightarrow \underset { Conjugate\quad Acid }{ { H }_{ 3 }O } +(aq)+\underset { Conjugate\quad Acid }{ OH-(aq) } \)

14.

2H₂+ O₂ ➝ 2H₂O
The isotope of hydrogen which has one proton and one neutron in its nucleus is Deuterium.
2D₂+ O₂ ➝ 2D₂O
The product is heavy water (Deuterium oxide). H₂O and D₂O have same chemical properties but the
reaction velocity of D2O is slightly less due to the difference in the mass number of the isotopes known as isotopic effect. Deuterium is heavier than protium so reacts slowly.

15.

(i) The element (A) is hydrogen reacts with carbon monoxide to form methanol (B).
CO + 2H₂ \(\overset{Cu}{\rightarrow}\) CH₃OH
(A) (B)
(ii) Hydrogen reacts with nitrogen to form ammonia (C).
\({ N }_{ 2 }+3{ H }_{ 2 }\quad \overset { 380-{ 450 }^{ 0 }C }{ \underset { 200/atm\quad 1le }{ \rightleftharpoons } } 2\underset { (C) }{ { NH }_{ 2 } } \)

A	H₂	Hydrogen
B	CH₃OH	Methanol
C	NH₃	Ammonia

16.

(i) A important peroxide is hydrogen peroxide (A).
(ii) H₂O₂ disproportionates to form oxygen and water.
\(\underset { (A) }{ { H }_{ 2 }{ O }_{ 2 } } \quad \longrightarrow { H }_{ 2 }O+\frac { 1 }{ 2 } { O }_{ 2 }\)
(iii) H₂O₂ reacts with FeSO₄ in acidic condition to form ferric sulphate (B).
2FeSO₄+ H₂SO₄+ H₂O₂➝ Fe₂(SO₄)₃+ 2H₂O
(A) (B)
(iv) H₂O₂ reacts with KMnO₄ in basic condition and form Manganese dioxide (C) and potassium hydroxide (D).
2KMnO₄+ 3H₂O₂➝ 2MnO₂+ 2KOH + 2H₂O + 3O₂
(A) (C) (D)

A	H₂O₂	Hydrogen peroxide
B	Fe₂(SO₄)₃	Ferric sulphate
C	MnO₂	Manganese dioxide
D	KOH	Potassium hydroxide

17.

(i) The universal solvent is water (A).
(ii) Water reacts with chlorine gas to form Hydrochloric acid (B) and Hypochlorous acid (C).
Cl₂+ H₂O ➝ HCl + HOCl
(A) (B) (C)
(iii) Water reacts with silicon tetrachloride (SiCI₄) to give silicon dioxide (D).
SiCl₄+ 2H₂O ➝ SiO₂+ 4HCl
(A) (D) (B)

A	H₂O	Water
B	HCl	Hydro chloric acid
C	HOCl	Hypo chlorous acid
D	SiO₂	Silicon dioxide

18.

(i) An element (A) belonging to group number 1 and period number 3 is sodium (A).
(ii) Sodium reacts with hydrogen to form sodium hydride (B)
2Na + H2 ➝ 2NaH
(A) (B) (C)
(iii) Sodium reacts with water to form sodium hydroxide (C).
2Na + 2H₂O ➝ 2NaOH + H₂
(A) (C)

A	Na	Sodium
B	NaH	Sodium hydride
C	NaOH	Sodium hydroxide

19.

Ortho and para hydrogen :

	Ortho Hydrogen	Para Hydrogen
1. Definition	Hydrogen molecule in which the protons in the nuclei of both H-atoms are known to spin in same direction is termed as ortho hydrogen.	If the protons in the nuclei of both H-atoms spin in opposite direction, it is termed as para Hydrogen
2. Composition	At room temperature ordinary hydrogen consists of about 75% ortho and 25% para form.	As the temperature is lowered, the equilibrium shifts in favour of para hydrogen. At 25K, there is 99% para and 1% ortho hydrogen
3. Melting Point	Melting point of ortho hydrogen is 13.95 K	Melting point of para hydrogen is 13.83K
4. Boiling Point	Boiling point of ortho hydrogen IS 20.39K	Boiling point of para hydrogen 20.26K
5. Vapour Pressure	The vapour pressure of ortho hydrogen is lower	The vapour pressure of liquid para hydrogen is higher than that of ordinary liquid hydrogen.
6. Magnetic Moment	Magnetic moment of ortho is twice than that of a proton	The magnetic moment of para hydrogen is zero since the spins neutralise each other
7. Internal molecular energy	Ortho hydrogen possesses a higher internal molecular energy	Para hydrogen possesses a lower internal molecular energy than ortho form

20.

(i) Over 90 % hydrogen produced in industry is used for synthetic applications. One such process is Haber process which is used to synthesis ammonia in large scales. Ammonia is used for the manufacture of chemicals such as nitric acid, fertilizers and explosives.
N₂+ 3H₂\(\overset { 380-450^{0}C }{ \underset {200atm/Fe }{ \rightleftharpoons } } \) 2NH₃
(ii) It can be used to manufacture the industrial solvent, methanol from carbon monoxide using copper as catalyst.
CO + 2H₂ \(\overset { Cu }{ \longrightarrow } \) CH₃OH
(iii) Unsaturated fatty oils can be converted into saturated fats called Vanaspati (margarine) by the reduction reaction with Pt/H₂.
(iv) In metallurgy, hydrogen can be used to reduce many metal oxides to metals at high temperatures.
CuO + H₂ ➝ Cu + H₂O
WO₃+ 3H₂ ➝ W + 3H₂O
(v) Atomic hydrogen and oxy-hydrogen torches are used for cutting and welding.
(vi) Liquid hydrogen is used as a rocket fuel.
(vii) Hydrogen is also used in fuel cells for generating electrical energy. The reversible uptake of hydrogen in metals is also attractive for rechargeable metal hydride battery.

21.

(i) Hydrogen liberates heat when it comes in contact with a metal. This property of hydrogen is used in atomic hydrogen welding and cutting torch.
(ii) Hydrogen reacts with unsaturated oil (Vegetable oil) in the presence ofNi catalyst. This property is used in the production of vanaspathi ghee.
(iii) Hydrogen combines with nitrogen in the ratio 3:1 in presence of Fe as catalyst and:
Mo as promoter. This property is used in the manufacture of ammonia . (Haber's process).
N₂+ 3H₂ \(\overset { 673k,200atm }{ \underset { Fe,Mo }{ \rightleftharpoons } } \) 2NH₃

22.

	H₂O	H₂O₂
Hybridisation of oxygen	SP³	Sp³ (each 0 - atom)
Structure

Generic 2

8 x 2 = 16

23.

Heavy water (D₂O) is the oxide of heavy hydrogen.

24.

Water containing bicarbonates, sulphates and chlorides of calcium and magnesium is called hard water.

25.

Halogens react with water to give an acidic solution. For example, chlorine forms hydrochloric acid and hypochlorous acid.
Cl₂(g) + H₂O(l) ➝ HCl (aq) + HOCl(aq)

26.

Steam when passed over hot iron gives iron oxide with the evolution of Hydrogen.
3Fe(s) + 4H₂O(l) ➝ Fe₃O₄(s) + H₂(g)

27.

(i) CO_(g)+ 2H_{2(g) \(\overset { Cu }{ \longrightarrow } \underset { Methanol }{ { CH }_{ 3 }{ OH }_{ (1) } } \)}
(ii) CH_4(g)+ H₂O_(g)\(\overset { 1270K }{ \underset { Ni }{ \rightarrow } } \)CO_(g)+ 3H_2(g)

28.

(i) H₂ has high energy per unit weight of fuel.
(ii) Burning of H₂ will not release any pollutants.
(iii) On combustion it forms water as a byproduct.
(iv) Fuel cells which use H₂ as fuel shows 70 to 85% higher efficiency than other fuel cells.

29.

Hydrogenation is an extremely important process in food industry. The addition of hydrogen to an alkene/ alkyne is called hydrogenation.
H₂C = CH₂(g) \(\longrightarrow\) H₃C - CH₃(g)

30.

The process of manufacture of ammonia is called Haber process, which is used for manufacturing nitric acid, fertilizers and explosives. Hydrogen combines with nitrogen in the ratio 3: 1 in presence of Fe as catalyst and Mo as promoter.
\({ N }_{ 2 }(g)+{ 3H }_{ 2 }(g)\rightleftarrows 2{ NH }_{ 2 }(g)\)