Chemistry

Chemical Reactions and Processes

626 Questions

Chemical reactions and processes questions cover the transformation of substances through electrolysis, thermal decomposition, and catalysis. Key areas include identifying gas evolution, balancing chemical equations, and understanding industrial chemical applications. This general chemistry topic is a staple in the science sections of multiple competitive examinations.

Thermal decompositionElectrolysis processGas evolution reactionsHeterogeneous catalystsFuel cell components

Chemical Reactions and Processes Questions

Multiple choice action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

Which of the following equation is not correct?

  1. Amphoteric oxide / Hydroxide + Acid$\rightarrow$ Salt + Water
  2. Amphoteric oxide / Hydroxide + Alkali$\rightarrow$ Salt + Water
  3. Metal + Alkali$\rightarrow$ Salt + Water
  4. Metal + Alkali$\rightarrow$ Salt + Hydrogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Metals generally do not react with alkalis to produce water; they react with alkalis to produce hydrogen gas and a salt (for amphoteric metals like Al or Zn). Therefore, 'Metal + Alkali -> Salt + Water' is incorrect.

Multiple choice chemistry study of the first element - hydrogen occurrence of hydrogen introduction to hydrogen hydrogen

Under suitable conditions, the following reaction:
Metal+Water $\xrightarrow [  ]{ Heat } $ Oxide or hydroxide of metal + Hydrogen 

may take place? Find which of the following metals, does not react in this way.

  1. Sodium

  2. Copper

  3. Iron

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

Because $Cu$ is placed below ${ H } _{ 2 }$ in reactivity series, hence cannot displace ${ H } _{ 2 }$. Hence reaction does not occur.

Multiple choice chemistry study of the first element - hydrogen occurrence of hydrogen introduction to hydrogen hydrogen

Dihydrogen can be prepared on a commercial scale by different methods. In its preparation by the action of steam on hydrocarbons, a mixture of $CO$ and $H 2$ gas is formed. It is known as __________.

  1. water gas

  2. syngas

  3. producer gas

  4. industrial gas
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

Steam reforming is a method for producing hydrogen, carbon monoxide, or other useful products from hydrocarbon fuels such as natural gas. This is achieved in a processing device called a reformer which reacts steam at high temperature with the fossil fuel.

Steam reforming of natural gas - sometimes referred to as steam methane reforming (SMR) - is the most common method of producing commercial bulk hydrogen. Hydrogen is used in the industrial synthesis of ammonia and other chemicals. At high temperatures (700 – 1100 °C) and in the presence of a metal-based catalyst (nickel), steam reacts with methane to yield carbon monoxide and hydrogen.

$C{ H } _{ 4 }+{ H } _{ 2 }O\leftrightharpoons CO+3{ H } _{ 2 }$

Multiple choice chemistry study of the first element - hydrogen occurrence of hydrogen introduction to hydrogen hydrogen

Which method is used to remove $CO$ from syngas($CO+H _2$) during Syngas Bosch process?

  1. Oxidation by using $KMnO _4$

  2. Oxidation by mixing steam
  3. Oxidation by using $K _2Cr _2O _7$

  4. All of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 This process of removal of $CO$ from syngas uses the water-gas shift reaction:

$CO + H _2O(steam) \longrightarrow CO _2 + H _2$

Multiple choice chemistry study of the first element - hydrogen occurrence of hydrogen introduction to hydrogen hydrogen

The formation of atomic hydrogen is favored at:

  1. high temperature and low pressure

  2. low pressure and high temperature

  3. high temperature and high pressure

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

The formation of atomic hydrogen is favored at high temperature and low pressure. The enthalpy of formation of atomic hydrogen is 217.97 kJ. This is the enthalpy change when a mole of atomic hydrogen is formed by dissociating 1/2 mole of molecular hydrogen (the more stable state of the element).)

Multiple choice chemistry study of the first element - hydrogen occurrence of hydrogen introduction to hydrogen hydrogen

Water gas is mixed with steam and the mixture is passed over heated $Fe _{2}O _{3}$ in presence of $Cr _{2}O _{3}.$
The mixture when passed in water dissolves $CO _{2}$ and dihydro gen left undissolved is collected. This method of preparation of hydrogen gas is known as:

  1. Bosch process

  2. Lane process

  3. Kellner process

  4. Hall process
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the commercial preparation of dihydrogen, Bosch process is used.


In Bosch's process, water gas (i.e. $CO+H _2$ ) is mixed with twice of its volume of steam in presence of catalysts $Fe _2O _3$ and $Cr _2O _3$ or $ThO _2$ where $Cr _2O _3$ acts as promoter. It gives the products $CO _2$ and $H _2$. Now, $CO _2$ is dissolved in water & removed leaving $H _2$ behind which is undissolved.

Multiple choice chemistry study of the first element - hydrogen occurrence of hydrogen introduction to hydrogen hydrogen

hydrogen peroxid  is not produced by the reaction :-

  1. $Na _2O _2 + dil.H _2SO _4$
  2. $Mg + H _2O$
  3. $BaO _2 + HCl$
  4. $BaO _2 + H _3PO _4$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sodium peroxide $\left( { Na } _{ 2 }{ O } _{ 2 } \right) $, when it reacts with sulphuric acid $\left( { H } _{ 2 }{ SO } _{ 4 } \right) $, it leads to the formation of sodium sulphate $\left( { Na } _{ 2 }{ SO } _{ 4 } \right) $ with hydrogen peroxide $\left( { H } _{ 2 }{ O } _{ 2 } \right) $.

${ Na } _{ 2 }{ O } _{ 2 }+{ H } _{ 2 }{ SO } _{ 4 }\longrightarrow { Na } _{ 2 }{ SO } _{ 4 }+{ H } _{ 2 }{ O } _{ 2 }$
Also, $Mg+{ H } _{ 2 }O\longrightarrow { Mg\left( OH \right)  } _{ 2 }$
${ BaO } _{ 2 }+HCl\longrightarrow Ba{ Cl } _{ 2 }+{ H } _{ 2 }{ O } _{ 2 }$
${ BaO } _{ 2 }+{ H } _{ 3 }{ PO } _{ 4 }\longrightarrow { Ba } _{ 3 }{ \left( { PO } _{ 4 } \right)  } _{ 2 }+{ H } _{ 2 }{ O } _{ 2 }$
Thus, in all of the above reactions, hydrogen peroxide $\left( { H } _{ 2 }{ O } _{ 2 } \right) $ is formed.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

$MCrO _{4(s)}\overset{CH _{3}COOH(aq)}{\rightarrow}MCrO _{4}$  ( Suspension) above change is correct for which metal ion (s) ? 

  1. $Ba^{2+},Sr^{2+},Ca^{2+}$
  2. $Ba^{2+},Sr^{2+}$
  3. Only $Ba^{2+}$
  4. $Sr^{2+},Ca^{2+}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Barium chromate (BaCrO4) is insoluble in water but dissolves in acidic solutions like acetic acid due to the formation of the dichromate ion. Strontium and calcium chromates are more soluble and do not behave as suspensions in the same way.

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

Nitro benzene is:
i) steam volatile 

ii) used as a solvent
iii) Aliphatic compounds 
Iv) lighter than water

  1. (i) and (ii) are correct

  2. (iii) and (iv) are correct

  3. (i) and (iii) are correct

  4. (i) and (iv) are correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nitro benzene is steam volatile and is used as solvent. But it is an aromatic compound and is heavier than water.