p-Block Elements Test

Result

p-Block Elements Test - 25

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Weekly Quiz Competition

Question 1
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Direction (Q. Nos. 1-10) This section contains 10 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
Q.
Which is incorrect statement?

A
Element with atomic number 52 belong to 5th period and 16th group

B
Number of electrons in the n and (n - 1) shells of selenium are 6 and 18

C
Among chalcogens oxygen and sulphur exist in free as well as in combined state

D
The differentiating electron in tellurium enters into 6p subshell

Solution

In tellurium, differentiating electron enters in to 5p subshell. Its valence shell configuration is 5s²5p⁴.
Question 2
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In earth’s crust, sulphur exists as

A
elemental sulphur

B
sulphide ore

C
sulphate ores

D
All of these

Solution

Sulphur exists in elemental form which is extracted by Frasch process.
Sulphide ores are zinc blende (ZnS), galena (PbS), copper pyrites (CuFeS₂), cinnabar (HgS),
Sulphate ores are gypsum (CaSO₄. 2H₂O), epsom (MgSO₄ .7 H₂O) .
Question 3
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The element used in the production of photocells and solar cells and also used in zerox machines is

A
sulphur

B
selenium

C
tellurium

D
polonium

Solution

Se is non-conductor in dark but acts as conductor when exposed to light.
Question 4
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The number of bond pairs and lone pairs in rhombic sulphur molecule are

A
6 and 6

B
8 and 8

C
8 and 16

D
16 and 8

Solution
Question 5
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Which has lowest bond energy (single bond)?

A
O—H

B
O—O

C
S—H

D
S—S

Solution

Presence of lone pairs on bonded atoms generally lowers the bond energy.
Bond energy order is
O—O (146) < (S—S) (266) < S—H(366) < O—H(464) kJ/mol
Question 6
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Harmful UV radiations emitted from the sun are prevented from reaching the earth by the presence of ozone in the

A
mesosphere

B
thermosphere

C
stratosphere

D
troposphere

Solution

Stratosphere layer strongly absorb harmful UV-radiations (λ. 255 nm).
Question 7
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Point out the incorrect statement among the following.

A
In OF₂, oxidation state of oxygen is + 2

B
Sulphur shows strong tendency to catenation while oxygen shows this tendency to a limited extent

C
The transition temperature of rhombic and monoclinic sulphur is 369°C

D
Oxygen is most abundant element in the earth's crust followed by sulphur in 16th group

Solution

It is 369 K or 96°C. The stable form at room temperature is rhombic sulphur which transforms to monoclinic sulphur when heated about 369 K.
Question 8
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The correct order of thermal stability of the hydrides of group 16 elements is

A
H₂Po> H₂Fe> H₂Se> H₂S > H₂O

B
H₂O2S>H₂Se>H₂Te>H₂Po

C
H₂O=H₂S=H₂Se-H₂Te=H₂Po

D
H₂O>H₂S>H₂SE>H₂Te>H₂Po

Solution

Thermal stability ∝ bond dissociation energy
(where, E = group 16 elements)
On moving down the group, bond dissociation energy decreases due to increase in bond length. Thus, the order of bond dissociation energy or thermal stability is
H₂O > H₂S > H₂Se > H₂Te > H₂PO
Question 9
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When O₂ changes to

A
paramagnetic become diamagnetic

B
bond length increases

C
diamagnetic become paramagnetic

D
bond order increases

Solution
Question 10
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Increasing order of oxidation number of oxygen is found in

A
KO₂ < BaO₂ < O₃ < O₂ F₂

B
O₃ < KO₂ < BaO₂ < O₂ F₂

C
BaO₂ < KO₂ < O₃ < O₂ F₂

D
O₂ F₂ < BaO₂ < KO₂ < O₃

Solution
Question 11
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Direction (Q. Nos. 11-13) Choices for the correct combination of elements from Column I and Column II are given as options (a), (b), (c) and (d), out of which one is correct.
Q.
Match the Column I with Column II and mark the correct option from the codes given below.

A

B

C

D

Solution
Question 12
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Match the Column I with Column II and mark the correct option from the codes given below.

A

B

C

D

Solution
Question 13
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Match the Column i with Column II and mark the correct option from the codes given below.

A

B

C

D

Solution
Question 14
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Direction : This section is based on Statement I and Statement II. Select the correct answer from the codes given below.
Q.
Statement I : Oxygen is more electronegative than sulphur, yet H₂S is acidic, while H₂O is neutral.
Statement II : H— S bond is weaker than O—H bond.

A
Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

B
Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I

C
Statement I is correct but Statement II is incorrect

D
Statement II is correct but Statement I is incorrect

Solution

H—S bond is weaker than H—O bond hence, H₂S is more acidic than H₂O.