Tag: chemistry

Questions Related to chemistry

State True or False.
Major sulphur dioxides production is through natural sources. 

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

The given statement is False.
 Major sulphur dioxides production is through following chemical processes
(1) By burning sulphur
$\displaystyle S+O _2 \rightarrow SO _2 \uparrow$
(2) By roasting zinc blende or iron pyrites.
$\displaystyle 2ZnS + 3O _2  \rightarrow 2ZnO+2SO _2 \uparrow$
$\displaystyle 4FeS _2+11O _2  \rightarrow 2Fe _2O _3+8SO _2 \uparrow $
(3) By heating anhydrite (calcium sulphate), obtained from gypsum with arbon above 1000 deg C.
$\displaystyle 2CaSO _4+C \rightarrow 2CaO+2SO _2 \uparrow+CO _2$

Sinks can _____ excess amount of sulphur dioxide.

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. Produce

  2. Breakdown

  3. Absorb

  4. Melt

Show answer
Correct Option: C
Explanation:

Sources of $SO _2$ include fossil fuel combustion by industry, biomass burning, volcanic release and the oxidation of dimethylsulphide (DMS) from the oceans. Major SO2 sinks are oxidation by OH and deposition onto wet surfaces. Sinks are the areas that can absorb excess amounts thus reducing its abundance in the environment.

Which of the following is not a sink of sulphur dioxide?

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. Ocean

  2. Wetlands

  3. Lakes

  4. None of above

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Correct Option: D
Explanation:

$SO _2$ sinks are oxidation by $OH$ and deposition on wet surfaces. Hence, oceans, wetlands and lakes are all sinks for sulphur dioxide.

High concentration of $SO _2$ leads to stiffness of flower buds.
chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

$SO _2$ is particularly poisonous to trees causing chlorosis and dwarfing. High concentration of $SO _2$ leads to stiffness of flower buds which then eventually fall off. Sulphur oxides $(SO _x)$ and sulphuric acid $(H _2SO _4)$ are related with the damage and destruction of vegetation, soil deterioration, construction material and watercourses.

Sulfur can be removed from coal during burning by using:

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. copper sulphate

  2. ferrous oxide

  3. both A and B

  4. limestone

Show answer
Correct Option: D
Explanation:

Sulfur can be removed from coal during burning by using limestone as a bed material in fluidized bed combustion. 

Select the correct statement (S).

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. p- chlorometaxylenol and dichlorometaxylenol are antibacterials and deodorants

  2. BHT and BHA are food antioxidants

  3. $SO _2$ and $SO _3^{-2}$ are antioxidants for wine and beers

  4. All of the above are correct statements

Show answer
Correct Option: D
Explanation:
(A) p-chlorometaxylenol & dichlorometaxylenol are antibacterials & deodrants as they are most effective against gram positive bacteris.
(B) BHA & BHT are antioxidants as oxygen reacts preferentially with BHA or BHT rather than oxidising fats or oils thereby protecting them from spoilage.
(C) $SO _{2} $ & $ SO _{3}^{2-}$ are used as preservative because of antioxidative & antimicrobial properties.

Which of the following acts as pickling agent?

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. $\displaystyle\;HNO _3$

  2. $\displaystyle\;HCl$

  3. $\displaystyle\;H _2SO _4$

  4. $\displaystyle\;HNO _2$

Show answer
Correct Option: C
Explanation:

Pickling is a metal surface treatment i.e; used to remove impurities such as strains, inorganic contaminants on the surface of the metal. So to remove this pickling liquor containing acid is used. 

$H _2SO _4$ is used as pickling agent because of its high oxidizing power, for which it can dissolve noble metals as well.

$1000L$ of air at STP was dissolved in water and required $2.5\times { 10 }^{ -5 }$ moles of $KMn{ O } _{ 4 }$ for complete reaction of ${SO} _{2}$ at pollutants. Thus, ${SO} _{2}$ content in air is :

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. $1.4ppm$

  2. $14ppm$

  3. $2.8ppm$

  4. $6.25ppm$

Show answer
Correct Option: A

A solution of chromium oxide in concentrated sulphuric acid is used for cleaning glass in laboratories because it:

chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

  1. Removes sand particles

  2. Oxidises grease

  3. Dissolves glass

  4. Reacts with dust

Show answer
Correct Option: B
Explanation:

Because a solution of chromium oxide in sulfuric acid (also known as a sulfochromic mixture or chromosulfuric acid) is a powerful oxidizing agent, it can be used to clean laboratory glassware, particularly of otherwise insoluble organic residues.They oxidize the grease present on the glass surfaces and hence thus it can be cleaned.

The dissociation energy of $CH _4$ and $C _2H _6$ are respectively 360 and 620 kcal /mole. the bond energy $C-C$ is:

chemistry energetics and thermochemistry bond energies and enthalpy changes bond enthalpies enthalpies for different types of reactions

  1. 260 kcal /mole

  2. 180 kcal /mole

  3. 130 kcal / mole

  4. 80 kcal / mole

Show answer
Correct Option: D
Explanation:
Dissociation of energy of $CH _4$ base
=$\cfrac {\text{dissociation energy of }{CH _4}}{4}=\cfrac {360}{4}=90Kcal/mole$

Dissociation energy of $C _2H _6$

620=1(B.E of C-C bond+ 6 B.E of C-H bond)

620=B.E of C-C bond +6 $\times $90

B.E of C-C bond=620-540=80 kcal / mole