Chemistry Test 79

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Chemistry Test 79

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Weekly Quiz Competition

Question 1
4 / -1

The expression to compute pH of NH₄CI solution is

A

B

C

D

Solution

NH₄Cl is a salt and it is formed from weak base NH₄OH and strong acid HCl (via neutralization reaction)

NH₄OH +HCl —-> NH₄Cl

Now, since HCl is a strong acid it will dissociate completely as well as rapidly and gives H+ n Cl-

And NH₄OH is a weak base, it will dissociate slowly.

So, at a particular time, H⁺ in the solution will be more as compared to NH₄⁺ n OH^-. Thus, solution will be acidic at that particular time.

Now if you want to know the pH value, you can use the following equation :

pH =0.5 {pKa -pKb -logC}

Hence, the correct option is (A).
Question 2
4 / -1

Given that ,respectively, which of the following orders regarding the reducing power of metals is correct?

A
Ag > Cr > Mg > K

B
Ag < Cr < Mg < K

C
Ag > Cr > K > Mg

D
Cr > Ag > Mg > K

Solution
Question 3
4 / -1

Which of the following electronic transitions in the line spectrum of He⁺ will have the same wavelength as that of the first line in the Lyman series of hydrogen atoms?

A
4 ← 2

B
2 ←1

C
3 ←1

D
4 ←1

Solution
Question 4
4 / -1

The IUPAC name of the given compound is

A
3-methyl-4-(prop-1-en-2-yl)phenol

B
3-methyl-4-(prop-1-en)phenol

C
2-methyl-4-(prop-1-en-2-yl)phenol

D
2-methyl-2-(prop-1-en-2-yl)phenol

Solution

Molecular Formula: C₁₀H₁₂O

IUPAC Name: 3-methyl-4-(prop-1-en-2-yl)phenol

Hence, the correct option is (A).
Question 5
4 / -1

Consider the stability of the following carbocation:

A. Cl₃C⁺

B. Cl₂CH⁺

C. ClCH²⁺

D. CH³⁺

A
D < A < B < C

B
A < B < C < D

C
D < A < C < B

D
D < B < A < C

Solution

Cl due to its -I effect further intensifies the +ve charge and thus destabilizes the carbocation. Thus, as the number of Cl atoms increases, the stability further decreases.

Hence, the correct option is (B).
Question 6
4 / -1

Molecular formula of Glauber's salt is-

A
MgSO₄.7H₂O

B
FeSO₄.7H₂O

C
CuSO₄.5H₂O

D
Na₂SO₄.10H₂O

Solution

Glauber’s salt is the decahydrate form of sodium sulfate. It is also known as mirabilite. The chemical formula of Glauber’s salt can be written as Na₂SO₄.10H₂O. Glauber’s salt is known to be a vitreous mineral with a white or colorless appearance that is formed as an evaporite from brines containing sodium sulfate.

Hence, the correct option is (D).
Question 7
4 / -1

Aspherical balloon of 21 cm diameter is to be filled up with H₂ at NTP from a cylinder containing the gas at 20 atm at 27^∘C. The cylinder can hold 2.82 liters of water at NTP. Calculate the number of balloons that can be filled up.

A
50

B
20

C
25

D
10

Solution
Question 8
4 / -1

A chelating agent has two or more than two donor atoms to bind to a single metal ion. Which of the following is not a chelating agent?

A
Thiosulphato

B
Oxalato

C
Glycinato

D
Ethane-1,2-diamine

Solution

The chelating ligand is a ligand that has two donor atoms to bind a single metal ion. Glycinato has 2 oxygen atoms as donor atoms. It is a chelating ligand. Oxalato has 2 oxygen atoms as donor atoms. It is a chelating ligand. Thiosulphate is an ambidentate ligand, not a chelating ligand.

Hence, the correct option is (A).
Question 9
4 / -1

Which of the reactions will need the maximum amount of energy?

A
Na → Na⁺+e^–

B
Ca⁺ → Ca⁺⁺+e^–

C
K⁺ → K⁺⁺+e^–

D
C²⁺ → C³⁺+e^–

Solution

If we write the configuration of species.

Configuration of Na = 1s², 2s², 2p⁶, 3s¹

here we see that one electron is present in the 3s subshell, it is incomplete so it can be ejected easily. So energy required to eject is very low.

Configuration of Ca⁺ = [Ar]4s¹ (incomplete 4s subshell),

So we can eject one more electron from its outermost shell. So energy required to remove it is also low but greater than Na.

Configuration of K⁺ = [Ar]4s⁰ [ inert gas configuration]

Here K⁺ ion has an inert gas configuration, which means it is a stable and very high amount of energy required to remove another electron.

Configuration of C²⁺ = 1s², 2s²

It is also a stable configuration and the energy required to remove another electron is high but the energy for it is not as high as the energy for K⁺.

So the maximum energy required to remove is for K⁺

Hence the correct option is (C).
Question 10
4 / -1

Which of the following is incorrect for primary amines?

A
On reaction with nitrous acid alkylamines produce alcohol

B
On reaction with nitrous acid arylamines produce phenol

C
Alkylamines are more basic than ammonia

D
Alkylamines are more basic than arylamines

Solution

Aryl amines react with nitrous acid to produce diazonium salts.

Hence, the correct option is (B).