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p-Block Elements

JEE Chemistry · 225 questions · Page 9 of 23 · Click an option or "Show Solution" to reveal answer

Q81
Which of the following oxoacids of sulphur contains "S" in two different oxidation states?
A H2S2O3
B H2S2O6
C H2S2O7
D H2S2O8
Correct Answer
Option A
Solution

In H2 S2O3\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}, sulphur exhibits two different oxidation states +6+6 and −2-2.

Q82
Nitrogen gas is obtained by thermal decomposition of :
A Ba(NO3)2
B Ba(N3)2
C NaNO2
D NaNO3
Correct Answer
Option B
Solution
Ba(N3)2⟶ΔBa+3 N2\mathrm{Ba}\left(\mathrm{N}_{3}\right)_{2} \stackrel{\Delta}{\longrightarrow} \mathrm{Ba}+3 \mathrm{~N}_{2}
Q83
Given below are two statements : Statement I : The pentavalent oxide of group-15 element, E2O5, is less acidic than trivalent oxide, E2O3, of the same element. Statement II : The acidic character of trivalent oxide of group 15 elements, E2O3, decreases down the group. In light of the above statements, choose most appropriate answer from the options given below :
A Both Statement I and Statement II are true.
B Both Statement I and Statement II are false.
C Statement I is true, but Statement II is false.
D Statement I is false, but Statement II is true.
Correct Answer
Option D
Solution

As +ve oxidation state increases, EN of element increases hence acidic character increases.

Down the group, non-metallic character decreases, acidic character decreases.

Acidic character : E2O5 > E2O3 Down the group, acidic character of E2O3 decreases.

Q84
The gas produced by treating an aqueous solution of ammonium chloride with sodium nitrite is :
A NH3
B N2
C N2O
D Cl2
Correct Answer
Option B
Solution

N2 gas is produced by treating an aqueous solution of ammonium chloride with sodium nitrite.

NH4Cl + NaNO2 → NaCl + N2 (g) ↑ + 2H2O

Q85
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Fluorine forms one oxoacid. Reason R : Fluorine has smallest size amongst all halogens and is highly electronegative. In the light of the above statements, choose the most appropriate answer from the options given below :
A Both A and R are correct and R is the correct explanation of A.
B Both A and R are correct but R is NOT the correct explanation of A.
C A is correct but R is not correct.
D A is not correct but R is correct.
Correct Answer
Option A
Solution

Due to its smaller size, fluorine forms only one oxoacid.

Both the Assertion and Reason are correct and The reason is the correct explanation.

Q86
Heating white phosphorus with conc. NaOH solution gives mainly :
A Na3P and H2O
B H3PO and NaH
C P(OH)3 and NaH2PO4
D PH3 and NaH2PO2
Correct Answer
Option D
Solution

P4 + 3NaOH + 3H2O →\to 3NaH2PO2 + PH3

Q87
Choose the correct stability order of group 13 elements in their + 1 oxidation state :
A Al < Ga < In < Tl
B Tl < In < Ga < Al
C Al < Ga < Tl < In
D Al < Tl < Ga < In
Correct Answer
Option A
Solution

Due to inert pair effect, stability of +3 oxidation state decreases and that of +1 oxidation state increases for (down the group) group 13 elements.

So, the correct order of stability of group 13 elements in their +1 oxidation state is Al < Ga < In < Tl.

Q88
The correct order of melting points of hydrides of group 16 elements is :
A H2S 2Se 2Te 2O
B H2O 2S 2Se 2Te
C H2S 2Te 2Se 2O
D H2Se 2S 2Te 2O
Correct Answer
Option A
Solution

Hydride M.P. H2O 273 K H2S 188 K H2Se 208 K H2Te 222 K

Q89
Consider the following reaction : A + alkali →\to B (Major Product) If B is an oxoacid of phosphorus with no P-H bond, then A is :
A White P4
B Red P4
C P2O3
D H3PO3
Correct Answer
Option B
Solution

Red P4 + Alkali →\to H4P2O6 (No P–H bond)

Q90
Which of the following elements is considered as a metalloid?
A Sc
B Pb
C Bi
D Te
Correct Answer
Option D
Solution

Sc, Pb, Bi are metals Te is a metalloid

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