Chemistry Test 186

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Chemistry Test 186

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Weekly Quiz Competition

Question 1
4 / -1

The average charge on each O atom and average bond order of S–O bond in SO₄^2– is :

A
–1 & 1.67

B
– 1/2 & 1.5

C
–1/2 & 1.67

D
–1/2 & 1.33

Solution
Question 2
4 / -1

Which is the right structure of XeF₄ ?

A

B

C

D

Solution

Lone pair - lone pair repulsion is maximum.So to minimize the repulsion the lone pairs occupy the positions which are trans to each other in the given octahedral geometry. Therefore, (C) option is correct.
Question 3
4 / -1

According to Molecular orbital theory which of the following is correct ?

A
LUMO level for C₂ molecule is orbital

B
In C₂ molecules both the bonds are π bonds

C
In C₂^2- ion there is one σ and π bonds

D
All the above is correct

Solution
Question 4
4 / -1

A diatomic molecule has a dipole moment of 1.2 D. If its bond distance is equal to 2.0Å then the % of ionic character in the diatomic molecular is :

A
12.5%

B
37%

C
52%

D
42%

Solution

Assuming complete charge transfer then dipole moment = (4.8 x 10^-10 esu) (10^-8 cm) x 2 = 9.6 D

so % ionic character
Question 5
4 / -1

Correct order of bond energy is:

A

B

C

D

Solution

Bond order is directly proportional to the bond energy.

Bond order of N₂ = 3 , N₂⁺, N₂^- = 2.5 N₂^2- = 2

But N₂^- has more electrons in antibonding MO's and thus N₂+ is more stable than N₂^-. So correct order of bond energy will be N₂> N₂⁺> N₂^-> N₂^2- Therefore, (A) option is correct
Question 6
4 / -1

Molecule XF₄ has non-zero value of dipole moment. Then X is :

A
Xe

B
Si

C
S

D
None

Solution
Question 7
4 / -1

Which of the following hydrogen bonds is the strongest ?

A
S – H ... O

B
O – H ... O

C
N – H ... N

D
F – H ... F

Solution

Strength of H–bond depends on the size and electronegativity of the atom.
Question 8
4 / -1

The correct order of boiling point is :

A

B

C

D

Solution

(i) H2O has highest boiling point because of H-bonding.

(ii) Boiling point also depends on the magnitude of van der Waal's force of attraction, which in turns depends on molecular weight of the compounds. Thus the correct order is H₂O > H₂T_e > H₂Se > H₂S.
Question 9
4 / -1

Which of the following statements is true for all the alkali metals ?

A
Their nitrates decomposes on heating to give the corresponding nitrites and oxygen.

B
Their chlorides crystallise as hydrates.

C
They react with water to form hydroxide and hydrogen.

D
They readily react with halogens to form ionic halides, M⁺X^–

Solution

(A) 4 LiNO₃ → 2Li₂O + 4NO₂ + O₂2NaNO₃ → 2NaNO₂ + O2 (similar decomposition with the nitrates of K, Rb and Cs)

(B) Only LiCI is deliquescent and crystallises as a hydrate LiCI.2H₂O

(C) 2M + 2H₂O → 2M⁺ + 2OH^- + H₂ (M = an alkali metal)

(D) Halides of Li are covalent in nature.
Question 10
4 / -1

Property of all the alkaline earth metals that increases with their atomic number is :

A
solubility of their carbonates

B
thermal stability of their sulphates

C
ionisation energy

D
electronegativity

Solution

(A), (C) and (D) decreases down the group but (B) increases down the group with increasing metallic character.