Chemistry

Chemical Reactions and Processes

571 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 chemical kinetics introduction to chemical kinetics understanding chemical kinetics rate of chemical reaction

A chemist puts a sample of dilute aqueous hydrochloric acid into beaker $1$. She adds a sample of zinc and measures the rate of production of hydrogen gas.
She then puts a different sample of dilute aqueous hydrochloric acid into beaker $2$. She adds a different sample of zinc and measure the rate of production of hydrogen gas.
The rate of the reaction in beaker $2$ is greater than the rate of the reaction in beaker $1$.
Which factors could help to explain this observation?
$1$. The reaction in beaker $1$ has a higher activation energy than the reaction in beaker $2$.
$2$. The zinc in beaker $1$ is in larger pieces than the zinc in beaker $2$.
$3$. The acid in beaker $1$ is at a lower concentration than the acid in beaker $2$.

  1. $1, 2$ and $3$ are correct
  2. $1$ and $2$ only are correct
  3. $2$ and $3$ only are correct
  4. $1$ only is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Since the rate of reaction in beaker $2$ is greater than the rate of reaction in beaker $1$, thus the concentration of acid in beaker $2$ will be greater than that in beaker $1$.
Also, lower the activation energy, the faster the rate of reaction. Thus the reaction in beaker $2$ has a lower activation energy than the reaction in beaker $2$.
Also the zinc in beaker $2$ will be in small pieces than that in beaker $2$ as large pieces will break slowly to react.
Hence $1, \; 2$ and $3$ are correct.
Multiple choice chemistry carbon compounds some important carbon compounds ethanol and ethanoic acid introduction to alcohols - ethanol

 When ethanol react with sodium,which gas will produce?

  1. hydrogen

  2. oxygen

  3. sodium ethoxide

  4. carbon dioxide
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If a small piece of sodium is dropped into some ethanol, it reacts steadily to give off bubbles of hydrogen gas and leaves a colourless solution of sodium ethoxide, $CH _3CH _2ONa$ and hydrogen gas is evolved.

$2C _2H _5OH + 2Na \rightarrow 2C _2H _5ONa + H _2$ Option A is correct.

Multiple choice chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

Product formed on electrolysis of potassium salt of fumaric and maleic acid is

  1. Ethene

  2. Ethane

  3. Butane

  4. Ethyne

  5. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electrolysis of the potassium salts of fumaric or maleic acid (unsaturated dicarboxylic acids) yields ethyne via Kolbe's electrolysis.