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 chemistry study of compounds a. hydrogen chloride laboratory method of preparation of hydrochloric acid physical and chemical properties and uses of hydrochloric acid hydrogen chloride: occurrence, preparation, purification and identification

$HCl$ gas cannot be dried by passing through:

  1. $H _{2}SO _{4}$
  2. $CaO$
  3. $P _{2}O _{5}$
  4. $CO$
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

$CaO$ and $P _2O _5$ are basic in nature so when $HCl$ is based over them, they will react with $HCl$ and form Salt and water, whereas $H _2SO _4$ and $CO$ are an acidic and hence greater affinity for water. So they can be used to dry $HCl$.

Multiple choice chemistry study of compounds a. hydrogen chloride laboratory method of preparation of hydrochloric acid physical and chemical properties and uses of hydrochloric acid hydrogen chloride: occurrence, preparation, purification and identification

$HCl$ is prepared by heating $NaCl$ with $conc.{ H } _{ 2 }S{ O } _{ 4 }$. But $HI$ cannot be prepared by treating $NaI$ with $conc.{ H } _{ 2 }S{ O } _{ 4 }$. Identify the reason.

  1. ${ H } _{ 2 }S{ O } _{ 4 }$ is oxidised by $HI$ and not oxidised by $HCl$
  2. $HI$ is oxidised by ${ H } _{ 2 }S{ O } _{ 4 }$ and $HCl$ is not oxidised by $HI$
  3. $HI$ dissociates on treatment with ${ H } _{ 2 }S{ O } _{ 4 }$ and $HCl$ does not dissociate
  4. Reaction of ${ H } _{ 2 }S{ O } _{ 4 }$ with $HI$ is reversible whereas with $HCl$ is irreversible
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$HCl$ is prepared by heating $NaCl$ with $conc.{ H } _{ 2 }S{ O } _{ 4 }$. But $HI$ cannot be prepared by treating $NaI$ with $conc.{ H } _{ 2 }S{ O } _{ 4 }$. Because  $HI$ is oxidised by ${ H } _{ 2 }S{ O } _{ 4 }$ and $HCl$ is not oxidised by $HI$.

Hence, option $B$ is correct.

Multiple choice aluminium patterns and properties of metals chemistry

Which of the following statement is incorrect?

  1. $Al$ reacts with excess $NaOH$ to give $Al{(OH)} _{3}$
  2. $NaH{CO} _{3}$ on heating gives ${Na} _{2}{CO} _{3}$

  3. Pure sodium metal dissolves in liquid ammonia to give blue solution
  4. $NaOH$ reacts with glass to give sodium silicate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium aluminate is also formed by the action of sodium hydroxide on elemental aluminium which is an amphoteric metal. The reaction is highly exothermic once established and is accompanied by the rapid evolution of hydrogen gas. The reaction is written as:
$2Al+2NaOH+{ 2H } _{ 2 }O\longrightarrow 2NaAlO _{ 2 }+3{ H }$

$2NaHCO _{ 3 (S) }\longrightarrow N{ a } _{ 2 }CO _{ 3 (S) }+CO _{ 2 (g) }+{ H } _{ 2 }O _{  (l) }$  This statment is correct.

By the reaction of sodium with liquid ammonia sodium ammide can be prepared.Sodium (alkali metal)dissolves in liquid ammoia solution to form a blue solution characteristic of a solvated electron in liquid ammonia, which is conducting in nature, due to ammoniated electrons (solvated electron).
This statment is correct.

Sodium silicate liquid can also be prepared directly by dissolving silica sand under pressure in a heated aqueous solution of caustic soda (sodium hydroxide, NaOH):
$2NaOH+{ SiO } _{ 2 }\longrightarrow Na _{ 2 }O.{ SiO } _{ 2 }+{ H } _{ 2 }O$
This statment is correct.

Multiple choice aluminium patterns and properties of metals chemistry

Which of the statement about aluminium is not correct?

  1. It liberates hydrogen from acid as well as alkalies

  2. It liberates hydrogen from acid but not from alkalies

  3. It liberates hydrogen from hot alkali solution

  4. It liberates hydrogen from boiling water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Solution:- (B) It liberates hydrogen from acid but not from alkalies

Aluminium is an amphoteric metal and hence it reacts with both acids as well as bases.
Reaction of $Al$ with acid-
$2 Al + HCl \longrightarrow 2 Al{Cl} _{3} + 3 {H} _{2}$
Reaction of $Al$ with base-
$2 Al + 2 NaOH + 2 {H} _{2}O \longrightarrow 2 NaAl{O} _{2} + 3 {H} _{2}$

Multiple choice aluminium patterns and properties of metals chemistry

Hydrogen gas will not be produced by :

  1. heated cupric oxide

  2. heated Ferric oxide

  3. heated stannic oxide

  4. heated aluminium oxide
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When alluminium oxide is heted it liberates oxygen gas
$2Al _2O _3\rightarrow 4Al+3O _2$
So alluminium oxide on heating do not produce hydrogen gas
Hence option D is correct.

Multiple choice aluminium patterns and properties of metals chemistry

A metal X reacts with aqueous NaOH solution to form Y and a highly inflammable gas. Solution Y is heated and $CO _2$ IS poured through it. Z precipitates out and $Na _2CO _3$ is formed. Z on heating gives $Al _2O _3$. Identify X, Y and Z.

  1. $Al-X$, $NaAlO _2 -Y$, $Al(OH) _3-Z$
  2. $Al _2O _3-X$, $NaAlO _2-Y$, $Al _2CO _3-Z$
  3. $Al _2O _3-X$, $[Na _2AlO _2]^+Oh^--Y$, $Al(OH) _3-Z$
  4. Al-X, $Al(OH) _3-Y$, $Al _2O _3-Z$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Solution:-

$X + NaOH(aq) \; \longrightarrow \; Y + \text{highly inflammable gas}$
$Y + CO _2 + H _2O \; \longrightarrow \; Z + {Na} _2CO _3$
$Z \; \xrightarrow [On \; heating] \; {Al} _2O _3$
${Al} _2O _3$ is formed when $Al{(OH)} _3$ is heated. 
$2Al{(OH)} _3 \; \xrightarrow [On \; heating] \; {Al} _2O _3 + 3H _2O$
Thus Z is $Al{(OH)} _3.$
When $NaAlO _2$ is heated and $ CO _2$ is poured through it, $Al{(OH)} _3$ precipitates out and $Na _2CO _3$ is formed.
$2NaAlO _2 + CO _2 + 3H _2O \; \longrightarrow \; 2Al{(OH)} _3 + {Na} _2CO _3$
Thus Y is $NaAlO _2$
When $Al$ reacts with aqueous $NaOH$ solution, it forms $NaAlO _2 \; and \; H _2 \; \text{(Highly inflammable gas)}$
$Al + NaOH(aq) \; \longrightarrow \; NaAlO _2 + H _2 \; \text{(highly inflammable gas)}$
Thus X is $Al$.
Hence, (A) is correct answer.

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 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 $Al{Cl} _{3}$ 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 $