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 evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

In an experiment oxygen was added to hydrogen and heated. On burning a substance containing both oxygen and hydrogen water was formed. What is this substance?

  1. Element

  2. Compound

  3. Solution

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

Oxygen and hydrogen are two elements and when they react they must generate another compound. Their product is not a mixture and  their result is a different compound with different properties.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Which of the following processes results in the formation of a new compound?

  1. Dissolving common salt in water

  2. Heating water

  3. Heating platinum rod

  4. Heating iron rod
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heating of any substance will give the same compound unless temperature is taken upto such high where the compound breaks down into its constituents. Dissolving common salt in water will give brine solution.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

In the manufacture of $NaOH$ by the electrolysis of $NaCl$ solution, the cathode and anode are separated using a diaphragm because :

  1. it prevents the reaction betweeen ${H _2}$ and $C{l _2}$ formed
  2. it prevents the mixing of $NaOH$ and $NaC{l _2}$
  3. it prevents the reaction betweeen $Na$ and $C{l _2}$ formed
  4. it increases the yield of $NaOH$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Which of the following is used to prepare $Cl _{2}$ gas at room temperature from concentrated $HCl$?

  1. $MnO _{2}$
  2. $H _{2}S$
  3. $KMnO _{4}$
  4. $Cr _{2}O _{3}$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Manganese dioxide($MnO _2$) is heated with concentrated $HCl$ to form $Cl _2$

$MnO _2+4HCl\rightarrow MnCl _2+Cl _2+2H _2O$

 $HCl$ in action with potassium permanganate gives $C _2$

$2KMnO _4+16HCl\rightarrow 2KCl+2MnCl _2+8H _2O+5Cl _2$.

Hence option A and C is correct.

Multiple choice group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

Identify the gas that would form when hydrobromic acid is combined with nickel (II) sulfide.

  1. $NiBr _{2}$
  2. $H _{2}S$
  3. $HBr$
  4. $NiS$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The gas that would form when hydrobromic acid is combined with nickel (II) sulfide is $H _2S$

$2 HBr(aq) + NiS(s)\rightarrow H _2S + NiBr _2$.
Hence option B is correct.
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

$H _2$ is not widely used as the reducing agent in metallurgic process because :

  1. many metals react with $H _2$ at elevated temperature forming hydrides
  2. there is a risk of explosion from $H _2$ and $O _2$ present in the air
  3. reducing power of $H _2$ does not increase with temperature
  4. reducing power of $H _2$, increases with temperature
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

$H _2$ is not widely used as the reducing agent in metallurgic process because metals react with $H _2$ at elevated temperature forming hydrides. When $H _2$ and $O _2$ present in the air are combined it will be explosive. Reducing power of $H _2$ does not increase with temperature, which is essential in metallurgy.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Carbon cannot be used to produce magnesium by chemical reduction of $MgO$ because:

  1. carbon is not a powerful reducing agent

  2. magnesium reacts with carbon to form carbides

  3. magnesium is less electropositive than carbon

  4. carbon does not react with magnesium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Magnesium is a very reactive metal. At the high temperatures required for carbon reduction, magnesium reacts with carbon to form magnesium carbide (MgC2), making the reduction process ineffective.

Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

After the reaction is over between adsorbed reactants, it is important to create space for the other reactant molecules to approach the surface and react. The process responsible for this is known as:

  1. sorption

  2. desorption

  3. physisorption

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

After the reaction is over between adsorbed reactants, the process of desorption is important to remove products and further create space for the other reactant molecules to approach the surface and react. 

Multiple choice chemistry energy rocks and minerals petroleum and natural gas fossil fuels

In cracking, reaction is propagated through:

  1. absorption of hydrogen by the formed radical

  2. release of hydrogen by the formed radical

  3. gain of electrons by the formed radical

  4. release of electron by formed radical
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In propagation step of cracking process, a free radical removes a hydrogen atom from another molecule, turning the second molecule into a free radical.

Multiple choice chemistry energy rocks and minerals petroleum and natural gas fossil fuels

In steam cracking, initiation usually involves breaking a chemical bond between:

  1. carbon and hydrogen atom

  2. carbon atoms

  3. carbon-hydrogen and carbon-carbon simultaneously

  4. no bond is completely broken in initiation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In steam cracking, initiation usually involves breaking a chemical bond between two carbon atoms, rather than the bond between a carbon and a hydrogen atom.