Chemistry

Chemistry of Gases and Applications

1,190 Questions

The chemistry of gases covers atmospheric composition, noble gases, and various applications of gas compounds in industrial and biological processes. Understanding the properties of common gases, their reactions, and environmental occurrences is vital for general science sections. Use these questions to practice identifying gases and their specific uses.

Atmospheric gasesNoble gasesGas applicationsChemical compounds

Chemistry of Gases and Applications Questions

Multiple choice chemistry mix and separate different types of mixtures homogenous and heterogenous mixtures all about mixtures

The mixture of gases used by deep-sea divers is helium-oxygen.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The main reason for adding helium to the breathing mixture is to reduce the proportions of nitrogen and oxygen below those of air, to allow the gas mixture to be breathed safely on deep dives. A lower proportion of nitrogen is required to reduce nitrogen narcosis and other physiological effects of the gas at depth.

Multiple choice chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

How many of the following metals when heated in an atmosphere of N2 gas form nitrides ?
Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba

  1. 9

  2. 5

  3. 3

  4. 6
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lithium (Li) and the alkaline earth metals (Mg, Ca, Sr, Ba) form nitrides when heated in nitrogen gas. Na, K, Rb, and Cs do not form stable nitrides under these conditions.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which of the following oxides cannot be reduced by coke?

  1. $Cu _2O,\: K _2O$
  2. $Fe _2O,\: ZnO$
  3. $CaO, \: K _2O$
  4. $PbO,\: Fe _3O _4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxides of strong elecropositive metals such as $K, Ca, Na, Al$ and $Mg$ are very stable. It is difficult to reduce them into metallic state by carbon reduction.
Such metals are extracted by passing electricity through their fused chlorides/oxides/hydroxides.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which one is mismatched ?

  1. Poling - refining of copper

  2. Cupellation - refining of silver

  3. Smelting - An oxidation process

  4. Roasting - An oxidation process
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Poling: The molten impure metal (Cu) containing oxides as impurities is stirred with green poles of wood which releases hydrocarbon gases. The hydrocarbon gases reduces oxide to metal. It is used in refining of copper.

Cupellation: Pb present in Ag is removed by this method. The impure metal is heated in a cupel or oval shaped crucible made of bone ash or cement and blast of air is passed over the molten mass. The impurities get oxidised and removed with the blast of air. It is used in refining of silver.

Smelting: The process of extraction of metal in its molten state by any reducing agent in presence of flux is called smelting. For example: oxides of less electropositive metals like Pb, Zn, Fe, Cu are reduced by any other reducing agents. Thus, smelting is a reduction process and not an oxidation process.

Roasting: The process in which the concentrated ore is heated in blast of air and ore gets converted into oxide and impurities like sulphur, arsenic are also oxidised to their oxides and is removed is called Roasting. It requires very high temperature and specialized furnace like Bessemer or reverberatory furnace. Thus, it is an ixidation process.



Multiple choice chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

Which of the following factors would favour the formation of ammonia?

  1. High pressure

  2. Low temperature

  3. High volume

  4. Low pressure
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
According to Le Chatelier's principle, high pressure would favour the formation of $NH _{3}$
$N _{2}$(g) + 3$H _2${g) $\leftrightharpoons$ $NH _{3}$(g)
The optimum conditions for the production of $NH _{3}$ are pressure of 200 x 10$^{5}$ Pa (about 200 atm) and temperature of -700 K.
In the given reaction, the number of moles of reactant is more than the product and according to the ideal gas equation, the pressure is inversely proportional to the number of moles.
Thus, by increasing pressure i.e. at high pressure, the reaction will proceed in a forward direction towards less number of moles. Thus the formation of the ammonia increases.
Multiple choice chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

Ammonia is dried over :

  1. Quick lime

  2. Slaked lime

  3. Phosphorus pentoxide
  4. Con. $\mathrm{H} _{2}\mathrm{S}\mathrm{O} _{4}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ammonia is dried by passing it over quick lime because it is a basic gas. Ammonia cannot be dried by conc. sulphuric acid or phosphorus pentaoxide as they will form ammonium sulphate or ammonium phosphate with it.

Multiple choice chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

Ammonia can be collected by displacement of

  1. Water
  2. $Conc.{ H } _{ 2 }S{ O } _{ 4 }$

  3. Brine

  4. Mercury
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ammonia is an extremely soluble gas and cannot be collected by displacement of water or acid. It can only be collected over a liquid in which it does not dissolve. 

One such liquid is mercury because it does not react with ammonia and it can be easily collected by displacement of the metal as it is liquid at room temperature. 

Multiple choice chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

Two major requirements for preparation of ammonia are

  1. Low temperature and high pressure

  2. Low temperature and present pressure

  3. High temperature and low pressure

  4. High temperature and high pressure
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This reaction is 

(a) reversible,

 (b) exothermic, and 

(c) proceeds with a decrease in volume.

According to the Le Chatelier's principle, the favorable conditions for the formation of ammonia are,

Low temperature

The temperature should be remain as low as possible, (although at unusually low temperatures, the rate of reaction becomes slow). It has been found that the temperature, which optimizes the yield of ammonia for the reaction, is maximum at about 500°C.

High pressure

Since Haber's process proceeds with a decrease in volume, it is favored by high pressure. In actual practice, a pressure of 200 - 900 atmospheres is employed.