Chemistry Test 142

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Chemistry Test 142

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Weekly Quiz Competition

Question 1
4 / -1

Match the hybrid bond orbitals of list I with the species of the list II and pick out the correct ?

A
A - 1 : B - 2 : C - 3 : D - 4

B
A - 1 : B - 2 : C - 4 : D - 3

C
A - 2 : B - 1 : C - 3 : D - 4

D
A - 2 : B - 1 : C - 4 : D - 3

Solution
Question 2
4 / -1

The electrochemical cell shown below is a concentration cell.
M|M²⁺ (saturated solution of a sparingly soluble salt, MX₂) ||M²⁺ (0.001 mol dm^-³) | M
The emf of the cell depends on the difference in concentrations of M²⁺ ions at the two electrodes. The emf of the cell at 298 K is 0.059 V.
The value of Δ G (kJ mol^-1) for the given cell is (Take 1 F = 96500 C mol^-1)

A
-5.7

B
5.7

C
11.4

D
-11.4

Solution
Question 3
4 / -1

First and second ionization energies of Magnesium are 7.646 and 15.035 eV respectively. The amount of energy in KJ needed to convert all the atoms of Magnesium into Mg²⁺ ions present in 12 mg of Magnesium vapours is :
[Given : 1 eV = 96.5 kJ mol^-1]

A
1.1

B
1.5

C
2.0

D
0.5

Solution
Question 4
4 / -1

The enthalpy change of the reaction is -57.3 kJ mol^-1. If the enthalpies of Formation of are zero and -285.84 kJ mol^-1 respectively, then the enthalpy of formation of

A
-228.54 kJ mol^-1

B
-333.14 kJ mol^-1

C
228.54 kJ mol^-1

D
333.14 kJ mol^-1

Solution
Question 5
4 / -1

Amongst the halides

(1) BCl₃
(2) AlCl₃
(3) GaCl₃
(4) InCl₃

The order of decreasing Lewis acid character is

A
1 > 2 > 3 > 4

B
4 > 3 > 2 > 1

C
3 > 4 > 2 > 1

D
2 > 3 > 4 > 1

Solution

Lewis acid strength of group 13 halides follow the order : BCl₃ > AlCl₃ > GaCl₃ > InCl₃.
As we move down the group, the size of atom increases, and as a result, the tendency to attract electrons decreases. This leads to a decrease in Lewis acid nature down the group
Question 6
4 / -1

A cationic colloidal electrolyte forms micelle at 10^-4 M concentration in water. If 1 mm³ solution contains 10¹² micelle structure, then the no. of cations involved in one micelle are NA = 6 × 10²³.

A
20

B
40

C
60

D
80

Solution

No. of particles of cationic colloidal electrolyte/litre before micelle formation = 10^-4 × 6 × 10²³ = 6 × 10¹⁹

∴ No. of particles of cationic colloidal electrolyte/mm³ = 6 × 10¹⁹ × 10^-6 = 6 × 10¹³

Number of micelles formed = 10¹² /mm³

∴ Number of cations in one micelle = 6 × 10¹³/10¹² = 60
Question 7
4 / -1

The half-life of a radioactive isotope is three hours. If the initial mass of the isotope were 256 g, the mass of it remaining undecayed after 18 hours would be

A
4.0 g

B
8.0 g

C
12.0 g

D
16.0 g

Solution
Question 8
4 / -1

Which of the above compounds are enantiomers?

A
II and III

B
III and IV

C
III and V

D
I and V

Solution

(i),(ii),(iv) have plane of symmetry, so they'll be meso compound. So its mirror image is identical.

Non-Mirror image to each other so III and V are enantiomers.
Question 9
4 / -1

Give the IUPAC name of :

A
2,2-Dimethyl-3-propyl-4-isopropylheptane

B
4-Isopropyl-5-t-butyl octane

C
4-t-Butyl-5-isopropyl octane

D
2-Methyl-3-propyl-4 isopropylheptane

Solution
Question 10
4 / -1

When H₂O₂ is added to ice cold solution of acidified potassium dichromate in ether and the contents are shaken and allowed to stand

A
A blue colour is obtained in ether due to formation of Cr₂(SO₄)₃

B
A blue colour is obtained in ether due to formation of CrO₅

C
A blue colour is obtained in ether due to formation of CrO₃

D
Chromyl chloride is formed

Solution

When H₂O₂ is added acidified potassium dichromate in ether solution, potassium dichromate is oxidised to blue peroxide of chromium (CrO₅) which is soluble in ether and produces blue coloured solution.
K₂Cr₂O₇ + H₂SO₄ + 4H₂O₂→ 2CrO₅ + K₂SO₄ + 5H₂O