Chemistry Test 78

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Chemistry Test 78

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Weekly Quiz Competition

Question 1
4 / -1

Which pair has same bond order :

A
N₂, NO

B
NO⁺, O₂^–

C
O₂⁺, O₂

D
N₂, NO⁺
Question 2
4 / -1

Body centred cubic and face centred cubic unit cells have n₁ and n₂ effective number of atoms. Which one of the following [n₁, n₂] combination is correct:

A
(4, 1)

B
(4, 2)

C
(1, 4)

D
(2, 4)

Solution

For bcc n₁ = 2 and for fcc n₂ = 4
∴ (n₁, n₂) or (2, 4)
Question 3
4 / -1

The limiting radius ratio for tetrahedral void is :-

A
0.414 to 0.732

B
0.225 to 0.414

C
0.155 to 0.225

D
0 to 0.155

Solution

Fact
Question 4
4 / -1

INCORRECT statement regarding solid material

A
Amorphous solids are isotropic in nature

B
Crystalline solids are anisotropic in nature

C
Like liquid, amorphous solids have tendency to flow

D
Crystalline solids are also known as pseudo solids
Question 5
4 / -1

Platinum crystallizes in a face-centered cubic crystal with a unit cell edge length 'a'. The distance between nearest neighbour atom is :

A
a

B
a √3/2

C
a √2/2

D
a √2/4

Solution

Distance between nearest neighbours is along the face diagonal = a √2/2.

Question 6

4 / -1

The bromination of acetone that occurs in acid solution is represented by

CH₃COCH₃(aq.) + Br₂(aq.) → CH₃COCH₂Br(aq.) + H⁺(aq.) + Br^– (aq.)

These kinetic data were obtained for given reaction concentration

Initial concentration			Initial rate of disappearance of Br₂
[CH₃COCH₃]	[Br₂]	[H⁺]	Initial rate of disappearance of Br₂
0.30	0.05	0.05	5.0 × 10^–5
0.30	0.10	0.05	5.0 × 10^–5
0.30	0.10	0.10	1.0 × 10^–4
0.90	0.05	0.10	3.0 × 10^–4

Based on these data, rate equation is -

Rate = k [CH₃COCH₃] [Br₂] [H⁺]²

Rate = k [CH₃COCH₃] [Br₂] [H⁺]

Rate = k [CH₃COCH₃] [H⁺]

Rate = k [CH₃COCH₃] [Br₂]

Solution

From (1) and (2),

[CH₃COCH₃] and [H⁺] = constant

[Br₂] = doubled

Rate = unchanged

∴ Order w.r.t. Br₂= 0

Possible rate law (By option)

r = k [CH₃COCH₃] [H⁺]

Question 7
4 / -1

For a reaction E_a = 0 and k = 3.2 × 10⁸s^–1 at 300K. The value of frequency factor at 400 K would be :-

A
6.4 × 10⁴s^–1

B
3.2 × 10⁴s^–1

C
3.2 × 10⁸s^–1

D
3.2 × 10⁵s^–1

Solution

K = A × e^–Ea/RT

if E_a = 0, K = A (independent of T)

∴ A = 3.2 × 10⁸
Question 8
4 / -1

A substance (initial concentration = a) reacts according to zero order kinetics. The time taken for the completion of reaction is nearly :-

A
a/k

B
a/2k

C
k/a

D
2k/a

Solution

t_completion = 2 × t_1/2

(∵ Rate is constt. in zero order)

t_completion = 2 × a/2k = a/k

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Re-Attempt Weekly Quiz Competition

Chemistry Test 78

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Chemistry Test 78

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Question 1

N2, NO

NO+, O2–

O2+, O2

N2, NO+

Question 2

(4, 1)

(4, 2)

(1, 4)

(2, 4)

Solution

Question 3

0.414 to 0.732

0.225 to 0.414

0.155 to 0.225

0 to 0.155

Solution

Question 4

Amorphous solids are isotropic in nature

Crystalline solids are anisotropic in nature

Like liquid, amorphous solids have tendency to flow

Crystalline solids are also known as pseudo solids

Question 5

a

a √3/2

a √2/2

a √2/4

Solution

Question 6

Rate = k [CH3COCH3] [Br2] [H+]2

Rate = k [CH3COCH3] [Br2] [H+]

Rate = k [CH3COCH3] [H+]

Rate = k [CH3COCH3] [Br2]

Solution

Question 7

6.4 × 104s–1

3.2 × 104s–1

3.2 × 108s–1

3.2 × 105s–1

Solution

Question 8

a/k

a/2k

k/a

2k/a

Solution

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N₂, NO

NO⁺, O₂^–

O₂⁺, O₂

N₂, NO⁺

Rate = k [CH₃COCH₃] [Br₂] [H⁺]²

Rate = k [CH₃COCH₃] [Br₂] [H⁺]

Rate = k [CH₃COCH₃] [H⁺]

Rate = k [CH₃COCH₃] [Br₂]

6.4 × 10⁴s^–1

3.2 × 10⁴s^–1

3.2 × 10⁸s^–1

3.2 × 10⁵s^–1