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Chemistry Test - 9

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Weekly Quiz Competition

Question 1
1 / -0

Consider the following skeleton equation:
__As₂O₃ + __SnCl₂+ __HCl → __SnCl₄ + __As + __H₂O
What are the stoichiometric coefficients of As₂O₃, SnCl₂, HCl, SnCl₄, As and H₂O, when the above equation is balanced?

A
1, 6, 3, 2, 3, 3

B
3, 2, 1, 6, 1, 2

C
1, 3, 6, 3, 2, 3

D
3, 2, 3, 1, 2, 6

Solution

The stoichiometric coefficients of As₂O₃, SnCl₂, HCl, SnCl₄, As and H₂O are 1, 3, 6, 3, 2 and 3, respectively.
As₂O₃ + 3SnCl₂ + 6HCl → 3SnCl₄ + 2As + 3H₂O
Question 2
1 / -0

If 10²¹ molecules are removed from 200 mg of CO₂, then the number of moles of CO₂ left will be

A
2.88*10^-3

B
1.66*10^-3

C
4,54*10^-3

D
3.341*10^-3

Solution
Question 3
1 / -0

The minimum amount of iron required to produce just sufficient hydrogen (by reaction with dil. HCl) to react completely with the oxygen obtained by heating 2.45 g KClO₃ is

A
2.52 g

B
3.36 g

C
3.00 g

D
2.50 g

Solution
Question 4
1 / -0

When a number 3.56923 *10³ is expressed in four significant figures, it becomes

A
3.5702 *10³

B
3.569 *10³

C
3.560 *10³

D
3.5692 *10³

Solution

When a number 3.56923 x 10³ is expressed in four significant figures, it becomes 3.569 x 10³.
Question 5
1 / -0

The decomposition of a certain mass of CaCO₃ gave 11.2 dm³ of CO₂ gas at STP. The mass of KOH required to completely neutralize the gas is

A
56 g

B
28 g

C
42 g

D
20 g

Solution
Question 6
1 / -0

Which of the following statements is incorrect?

A
A metal that crystallises in bcc structure has a coordination number 12.

B
The coordination number of each type of ion in CsCl is 8.

C
A unit cell of an ionic crystal shares some of its ions with other unit cells.

D
The length of the unit cell in NaCl is 552 pm (^rNa⁺ = 95 pm, ^rCl^- = 181 pm).

Solution

BCC structure of metals is shown below. The metal atom at the centre of the body is surrounded by 8 metal atoms that are at the corners of the cube. Hence, option (1) is incorrect.

The crystal structure of CsCl forms a major structural type where each cesium ion is coordinated by 8 chlorine ions as shown below.

Thus, option (2) is correct.

Every unit cell shares some of its atoms/ions with other unit cells. So, option (3) is also correct.

In unit cell of NaCl, the Cl^- ions are arranged at the corners as well as at the centres of the faces, while the Na⁺ ions occupy the centres of the edges along with a position at the body centre.

The Na⁺ and Cl^- ions are touching each other along the edge of the unit cell.

So, edge length =2r_Na⁺+ 2r_cl^-

= (2 x 95) + (2 x 181) = 552 pm

Therefore, option (4) is also correct.
Question 7
1 / -0

How many unit cells are present in a cube shaped ideal crystal of NaCl of mass 1.00 g? [Atomic masses : Na = 23 u, Cl = 35.5 u]

A
5.14 *10²¹

B
2.57 * 10²¹

C
1.28 * 10²¹

D
1.71 *10²¹

Solution
Question 8
1 / -0

NH₃ gas at 1 atm and HCl gas at P atm are allowed to effuse at room temperature through identical pinholes from opposite ends of a glass tube of 1 m length and uniform cross-section. NH₄Cl is first formed at a distance of 60 cm from the end, through which HCl gas is sent into the tube. What is the value of P?

A
4.83 atm

B
1.298 atm

C
1 atm

D
2 atm

Solution

The pressures of the gases are different, but their temperature is constant. Therefore, the rate of effusion of the gas molecules will be directly proportional to the square root of the pressure and is inversely proportional to the square root of the molecular mass according to Graham`s law.

Thus, combining the two, we have
Question 9
1 / -0

The gases which diffuse at the same rate under the same temperature and pressure conditions are

A
CO and NO

B
NO₂ and CO₂

C
NH₃ and PH₃

D
NO and C₂H₆

Solution
Question 10
1 / -0

Dalton's law of partial pressure is applicable to which of the following systems?

A
NH₃ + HCl

B
NO + O₂

C
H₂ + N₂

D
CO + H₂

Solution
Question 11
1 / -0

For N₂(g) + 3H₂(g) ⇌ 2NH₃(g), H is equal to

A
ΔE + 2RT

B
ΔE - 2RT

C
ΔE + RT

D
ΔE - RT

Solution

We know that ΔH = ΔE + ΔnRT
In the present case, Δn = - 2
ΔH = ΔE - 2RT
Question 12
1 / -0

Which of the following pairs has the highest heat of neutralisation?

A
NH₄OH and CH₃COOH

B
NH₄OH and HCl

C
KOH and CH₃COOH

D
KOH and HCl

Solution

Since both acid and base are strong in this case. So heat of neutralization is highest in this case.
Question 13
1 / -0

Directions: In the following question, a statement of Assertion is given; followed by a corresponding statement of Reason just below it. Of the statement mark the correct answer as:
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) If assertion is true statement, but reason is false.
(d) If both assertion and reason are false.
Assertion: Molar entropy of vaporisation of water is different from ethanol.
Reason: Water is more polar than ethanol.

A
(a)

B
(b)

C
(c)

D
(d)

Solution

Molar entropy of vaporisation of water is different from ethanol. Molar entropy is independent of polarity of the molecule.
Question 14
1 / -0

Standard enthalpies of formation of CO₂ (g), CO (g), N₂O (g) and NO₂(g) in kJ/mol are -393, -110, 81 and 34, respectively. What is the value of (in kJ) in the following reaction?
2NO₂ (g) + 3CO (g) N₂O (g) + 3CO₂(g)

A
–836

B
–1460

C
–1460

D
836

Solution

By using the formula:
D_H for the reaction = [Sum of heat of formation for products] - [Sum of heat of formation for reactants]
The value comes out to be –836 kJ.
Question 15
1 / -0

In which of the following processes, maximum increase in entropy is observed?

A
Melting of ice

B
Sublimation of naphthalene

C
Condensation of water

D
Condensation of water

Solution

Entropy of gaseous phase is maximum. So sublimation of naphthalene will involve maximum entropy increase.

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Chemistry Test - 9

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Question 1

1, 6, 3, 2, 3, 3

3, 2, 1, 6, 1, 2

1, 3, 6, 3, 2, 3

3, 2, 3, 1, 2, 6

Solution

Question 2

2.88*10-3

1.66*10-3

4,54*10-3

3.341*10-3

Solution

Question 3

2.52 g

3.36 g

3.00 g

2.50 g

Solution

Question 4

3.5702 *103

3.569 *103

3.560 *103

3.5692 *103

Solution

Question 5

56 g

28 g

42 g

20 g

Solution

Question 6

A metal that crystallises in bcc structure has a coordination number 12.

The coordination number of each type of ion in CsCl is 8.

A unit cell of an ionic crystal shares some of its ions with other unit cells.

The length of the unit cell in NaCl is 552 pm (rNa+ = 95 pm, rCl- = 181 pm).

Solution

Question 7

5.14 *1021

2.57 * 1021

1.28 * 1021

1.71 *1021

Solution

Question 8

4.83 atm

1.298 atm

1 atm

2 atm

Solution

Question 9

CO and NO

NO2 and CO2

NH3 and PH3

NO and C2H6

Solution

Question 10

NH3 + HCl

NO + O2

H2 + N2

CO + H2

Solution

Question 11

ΔE + 2RT

ΔE - 2RT

ΔE + RT

ΔE - RT

Solution

Question 12

NH4OH and CH3COOH

NH4OH and HCl

KOH and CH3COOH

KOH and HCl

Solution

2.88*10^-3

1.66*10^-3

4,54*10^-3

3.341*10^-3

3.5702 *10³

3.569 *10³

3.560 *10³

3.5692 *10³

The length of the unit cell in NaCl is 552 pm (^rNa⁺ = 95 pm, ^rCl^- = 181 pm).

5.14 *10²¹

2.57 * 10²¹

1.28 * 10²¹

1.71 *10²¹

NO₂ and CO₂

NH₃ and PH₃

NO and C₂H₆

NH₃ + HCl

NO + O₂

H₂ + N₂

CO + H₂

NH₄OH and CH₃COOH

NH₄OH and HCl

KOH and CH₃COOH