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12th Grade > Chemistry

P-BLOCK GROUP 16 - CHALCOGENS MCQs

Total Questions : 14 | Page 1 of 2 pages
Question 1. Compared to other group 16 elements, the anomalous behavior of Oxygen is due to:
  1.    Small atomic size
  2.    High electronegativity
  3.    Both (A) and (B)
  4.    None of these
 Discuss Question
Answer: Option C. -> Both (A) and (B)
:
C
Among the Chalcogens, Oxygen shows considerable anomalies. For instance, Oxygen exists as a diatomic gas while the other chalcogens are all solids at room temperature and 1atm pressure. Further, oxygen forms strong and stablepπpπdouble bonds (as in the case of O2 molecule) whereas the other elements tend not to. Also, the Oxygen - Oxygen single bond is weaker compared to the Element - Element single bonds of other chalcogens.
All this can be attributedto the small atomic size and high electro negativity of Oxygen.
Question 2. For which of the following process is Oxygen a prerequisite?
  1.    Inspiration
  2.    Expiration
  3.    Both (A) and (B)
  4.    Inspiration and combustion
 Discuss Question
Answer: Option D. -> Inspiration and combustion
:
D
Oxygen is the major constituent during inspiration (inhalation) and combustion because both these processes cannot occur without oxygen. Oxygen from inspiration is used to combust the food to release energy and any fuel when combusted, releases energy. Hence oxygen is a must for combustion.
Question 3. Which of the following Chalcogens shows the highest tendency for catenation?
  1.    Tellurium
  2.    Sulphur
  3.    Oxygen
  4.    Polonium
 Discuss Question
Answer: Option B. -> Sulphur
:
B
Among the chalcogens, Sulphur exhibits the greatest tendency for catenation owing to the SS bond stability.
Question 4. For patients who suffer from low oxygen levels, only "humidified oxygen" is supplied as opposed to dry oxygen gas - True or False?
  1.    True
  2.    False
  3.    Both (A) and (B)
  4.    Inspiration and combustion
 Discuss Question
Answer: Option A. -> True
:
A
If the oxygen gas is not Humidified before entering patient’s body, it then causes drying of upper respiratory tract. Therefore, always humidified oxygen is used in hospitals to supply to the patients.
Question 5. We humans have known elemental Sulphur from the earliest times. In the last two decades, the allotropy of sulfur has been explored in great detail. The most common naturally occurring allotrope,S8 cyclo-octasulphur, has a puckered three dimensional “crown” like arrangement of atoms around the ring. This homocyclic allotrope forms “needle-like” crystals above 95 C, but below that temperature, crystallizes in a “chunky” fashion. The crystals, which are referred to as monoclinic and rhombic forms, differ simply in the way in which the molecules pack. These are allotropes of each other – True or False?
  1.    True
  2.    False
  3.    Oxygen
  4.    Polonium
 Discuss Question
Answer: Option B. -> False
:
B
The question looks long for a true or false type doesn’t it. Shall we keep the answer very short – yes?
Polymorphs are defined as different crystal forms in which identical units of the same compound are packeddifferently. Strictly speaking, the three varieties of cyclo-octasulphur – the α-Sulphur, β-Sulphur and the γ-Sulphur are all polymorphs andnot allotropes. Allotropes contain different molecular units!
The repeating molecular unit of cyclo-octasulphur – the S8molecule looks like:
We Humans Have Known Elemental Sulphur From The Earliest Tim...
Question 6. Finely divided metals and metal oxides on reaction with hydrogen peroxide liberate __ gas.
 Discuss Question

:
Hydrogen peroxide readily breaks down in the presence of finely divided metals to liberate oxygen gas:
2H2O2+Metal2H2O(l)+O2(g)
Question 7. Of the given hydrides of group 16 Elements, which is the most stable thermodynamically?
  1.    H2Te
  2.    H2S
  3.    H2O
  4.    H2Se
 Discuss Question
Answer: Option C. -> H2O
:
C
As we go down the group, the electronegativity of the central atom decreases while the atomic size increases. This causes the EH bond to weaken as we go down the group. Hence the thermal stability order is as H2O>H2S>H2Se>H2Te>H2Po
Question 8. Sulphur trioxide gas is an important precursor to manufacture sulphuric acid. It is produced by the catalytic oxidation of SO2 gas. Which of the following are suitable catalysts for the process?
  1.    Probiotic yoghurt
  2.    Sodium vapour
  3.    X-rays
  4.    V2O5
 Discuss Question
Answer: Option D. -> V2O5
:
D
2SO2(g)+O2(g)2SO3(g):ΔH=197kJ.mol1
In the contact process for the manufacture of Sulphuric acid, V2O5 is the preferred catalyst for the above reaction. Earlier, platinated asbestos was used. As can be seen from the above equation, the enthalpy change is negative which implies that the reaction should be favoured in the forward direction for lower temperatures. However, in real scenarios a lower temperature could bring down the rate of the oxidation to unfeasible levels. So we don’t mind conducting the reaction at 450C and 1-2 atm pressure. Do note that the catalyst only accelerates the rate of the reaction without altering the position of the chemical equilibrium.
First the V5+ ions oxidize SO2 (g) into SO3 (g) and themselves get reduced to V4+ ions. Naturally the doubt arises as to whether this involvement of Vanadium ions affects the equilibrium. Through catalyst regeneration, the V4+ ions are oxidized back to V5+ ions such that Vanadium ions are not part of the overall reaction!
Question 9. Sulphur can also exist in an amorphous form – True or False?
  1.    True
  2.    False
  3.    Oxygen
  4.    Polonium
 Discuss Question
Answer: Option A. -> True
:
A
When heated to 113COrthorhombic sulphur melts and if we continue heating this molten yellow liquid, it darkens above 160Cand becomes more viscous as the Sulphur rings break open and polymerize. The resulting helical Snpolymers can be extracted from the melt by pouring the molten Sulphur in water (called quenching). This super-cooled liquid is a metastable rubber-like material that slowly converts back to stable αS8at room temperature. Different polymeric chains can have different number of atoms and isolating a particular strain becomes difficult. Obviously these polymeric forms are amorphous
Question 10. Among the group 16 elements, Oxygen exhibits the widest variety of allotropy – True or False?
  1.    False
  2.    True
  3.    Oxygen
  4.    Polonium
 Discuss Question
Answer: Option A. -> False
:
A
Generally, Oxygen exists in the form of only two allotropes – dioxygen and trioxygen, which is also known as ozone. Sulphur exhibits a tremendous variety in terms of allotropy. There are many allotropes for Sulphur. Also, the other elements like Se and Te exist in the form of several allotropes.

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