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 salts salts and their classification acids, bases and salts chemistry

Sodium hydroxide reacts with nitric acid to give a soluble salt which is _________.

  1. $NaNO$
  2. $NaNO _2$
  3. $NaNO _3$

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$  Sodium\ hydroxide + Nitric\ acid \rightarrow Sodium\ nitrate + Water  $
$  NaOH(aq) + HNO _3(aq)  \rightarrow  NaNO _3(aq) + 2H _2O(l)   $
Sodium nitrate thus formed is a soluble salt.
 

Multiple choice salts salts and their classification acids, bases and salts chemistry

$  Zn + H _2SO _4 \rightarrow     $
What is the salt produced? What is the solubility of the salt?

  1. $ZnSO _4$, soluble
  2. $ZnSO _4$, insoluble
  3. $ZnSO _2$, soluble
  4. $ZnSO$, insoluble
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Reacting an acid with a metal or with an insoluble base gives a soluble salt. 
$  Zn + H _2SO _4 \rightarrow        ZnSO _4     +  H _2  $

Multiple choice salts salts and their classification acids, bases and salts chemistry

Which type of reaction produces precipitates which are ionic compounds?

  1. Decomposition

  2. Double Replacement

  3. Synthesis

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

Double replacement reactions, also called as double displacement, exchange or metathesis reactions occur when parts of ionic compounds are exchanged, making two new compounds.

However, if during this reaction, a product is formed such that it is insoluble in water then it leads to precipitation of the product. There is a formation of an insoluble mass at the bottom of the test tube which is known as the precipitate. 
An example of the double replacement reaction where an ionic compound is precipitated is:-
$BaCl _2+Na _2SO _4 \rightarrow BaSO _4+2NaCl$
Here, $BaSO _4$ is an ionic product that forms an insoluble white mass as it is insoluble in water.
Hence, the correct answer is the option (B).

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

 Protolysis is transfer of:

  1. Hydroxide ions

  2. Water molecules

  3. Anions

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

protolysis (proton-transfer) reaction that takes place with very weak protonic acids, including water.


Protolysis $\to$ Transfer of $H^{+}$ ion and breaking of bonds by it.

Option D is correct.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Which of the following statements is not correct?

  1. Copper liberates hydrogen from acids

  2. In its higher oxidation states, manganese forms stable compounds with oxygen and fluorine
  3. $Mn^{3+}$ and $Co^{3+}$ are oxidising agents in aqueous solution
  4. $Ti^{2+}$ and $Cr^{2+}$ are reducing agents in aqueous solution
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Copper has a positive standard reduction potential, meaning it cannot displace hydrogen from acids. Therefore, it does not liberate hydrogen gas from acids.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Process that produces soap from fats is called as:

  1. acidification

  2. saponification

  3. hydrolysis

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

Soaps are sodium or potassium salts of long chain fatty acids. When triglycerides in fat/oil react with aqueous $NaOH$ or $KOH$, they are converted into soap and glycerol. This is called alkaline hydrolysis of esters. Since this reaction leads to the formation of soap, it is called the Saponification process.

Multiple choice chemistry mix and separate different types of solutions various mixtures introduction to solutions

Highly pure dilute solution of sodium in liquid ammonia:

  1. on evaporation yield metals.

  2. exhibits electrical conductivity.

  3. produces sodium amide and hydrogen gas instantly.

  4. acts as powerful reducing agent.
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

$M+(x+y)NH _3\rightarrow [M(MH _3) _x]^++[4(NH _3) _y]^-$. Blue colour of the solution is due to ammoniated electrons and good conductor of electricity because of both ammoniated cations and ammoniated electrons.

Multiple choice chemistry mix and separate different types of solutions various mixtures introduction to solutions

Hydrogen gas adsorbed on surface of platinum is an example of solid in gas solution.

  1. True

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

Platinum is present in solid state and when hydrogen gas is adsorbed on the surface of platinum then they are forming solid in gas solution because soild is very  small and is present as solute and the amount of gas adsorbed is much more then platinum so it act as solvent and complete solution is known as solid in gas.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Anhydrous $AlCl _{3}$ is formed in:

  1. $AlCl _{3}.6H _{2}O \xrightarrow[]{\Delta}$
  2. $Al(red hot) + HCl(moist)\xrightarrow[]{\Delta}$
  3. $Al _{2}O _{3} + C+ Cl _{2}(dry) \xrightarrow[]{\Delta}$

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

Anhydrous aluminium chloride cannot be obtained by heating its hydrated form because hydrolysis yields alumina and hydrochloric acid instead. It is industrially prepared by passing dry chlorine gas over a heated mixture of alumina and carbon.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Anhydrous $Al{Cl} _{3}$ cannot be obtained from which of the following reactions :

  1. Heating $Al{Cl} _{3}.6{H} _{2}O$
  2. By passing dry $HCl$ over hot aluminium powder
  3. By passing dry ${Cl} _{2}$ over hot aluminium powder
  4. By passing dry ${Cl} _{2}$ over hot mixture of alumina and coke
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

On heating $AlCl _{ 3 }.6{ H } _{ 2 }O$ hydrolysis takes place to produce $Al\left( OH \right) _{ 3 }$ and $HCl$
and on further heating $Al\left( OH \right) _{ 3 }$ converts to $Al _{ 2 }O _{ 3 }$.

By passing dry $HCl$ or ${ Cl } _{ 2 }$ over heated aluminium,
$2Al+3C{ l } _{ 2 }\longrightarrow 2AlC{ l } _{ 3 }$

$2Al+6HC{ l }\longrightarrow 2AlC{ l } _{ 3 }+3{ H } _{ 2 }$

Macah's method:$Al _{ 2 }O _{ 3 }+3C+3{ Cl } _{ 2 }(dry)\xrightarrow [ \Delta  ]{  } 2AlC{ l } _{ 3 }+3CO\uparrow $

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Which reaction cannot give anhydrous $AlCl _3$ ?

  1. Heating of $AlCl _3.\, 6H _2O$

  2. Passing dry HCl over heated aluminium powder
  3. Passing dry $Cl _2$ over heated aluminium powder
  4. Heating a mixture of alumina and coke in a current of dry $Cl _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Aluminium chloride reacts with water to form  hexahydrate. The anhydrous phase cannot be regained on heating as HCl is lost leaving aluminium hydroxide or alumina.
$Al\left( { H } _{ 2 }O \right) _{ 6 }{ Cl } _{ 3 }\rightarrow { Al\left( OH \right)  } _{ 3 }+3HCl+{ 3H } _{ 2 }O$

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Anhydrous $AlCl _3$ is prepared by :

  1. reaction of HCl and Al metal

  2. reaction of dry HCl and heated Al metal
  3. passing $Cl _2$ gas over heated Al metal
  4. reaction of $Al _2O _3$ with dil HCl.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Answer:- (B) reaction of dry $HCl$ and heated $Al$ metal.
Aluminium chloride is manufactured on a large scale by the exothermic reaction of heated aluminium metal with dry hydrogen chloride at temperatures between $650$ to $750 ^0C$
$2Al + 6HCl \; \longrightarrow \; 2Al{Cl} _3 + 3{H} _2$
Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Anhydrous $AlCl _3$ fumes in air. What is the reason for it?

  1. It is hygroscopic in nature

  2. It gives out chlorine when exposed to air.
  3. It is hydrolysed in moist air giving out fumes of $HCl$.

  4. It loses water when exposed to moist air.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
White fumes are due to the presence of $HCl$ gas.

Anhydrous aluminium chloride is hydrolysed partially with the moisture in the atmosphere to give $HCl$ gas. 

This HCl combines with the moisture in the air and appears white in colour.

$Al{Cl} _3 + 3H _2O \; \longrightarrow \; Al{(OH)} _3 + 3HCl \text{(white fumes)}$

Hence, the correct answer is option $\text{C}$.
Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Which reaction cannot give anhydrous $AlCl _{3}$

  1. Heating of $AlCl _{3}.6H _{2}O$
  2. Passing dry $HCl$ over heated aluminium powder
  3. Passing dry $Cl _{2}$ over heated aluminium powder
  4. Heating a mixture of alumina and coke in a current of dry $Cl _{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Option A is correct because heating of $AlCl _{3}.6H _{2}O$ do not produce anhydrous $AlCl _{3}$ on heating

$AlCl _{3}.6H _{2}O\rightarrow Al _{2}O _{3}+HCl+H _{2}O$
Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Which of the following statement about anhydrous aluminium chloride is correct?

  1. Its anhydrous form is deliquescent and fumes in air.

  2. It is not easily hydrolyzed.
  3. It sublimes at $20^0C$ under vaccum.

  4. It is a strong Lewis base.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Aluminium chloride is hygroscopic, having a very pronounced affinity for water. It fumes in moist air and hisses when mixed with liquid water as the Cl ions are displaced with $H _2O$ molecules in the lattice to form the hexahydrate $AlCl _36H _2O$ (also white to yellowish in color).

It is  easily hydrolyzed.

It do not sublimes at $20^0C$ under vacuum.

It is a strong Lewis acid.(it accepts electrons)

So option A only is correct

Hence option A is correct statement.