Chemistry

Chemical Reactions and Equations

674 Questions

Chemical reactions and equations form a foundational chemistry topic where students identify reaction products, balance chemical formulas, and classify reaction types. It covers critical mechanisms like Markovnikov's rule, precipitation, and endothermic or exothermic processes. These questions are highly common in general science sections of state and central government competitive exams.

Endothermic reactionsPrecipitation reactionsDehydrohalogenation of alkyl halidesChemical equation balancingReaction product identification

Chemical Reactions and Equations Questions

Multiple choice chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

To what type of reaction does the activity series apply?

  1. Synthesis

  2. Single replacement

  3. Double replacement

  4. Decomposition
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

An activity series is a list of substances ranked in order of relative reactivity. For example, magnesium metal can knock hydrogen ions out of solution, so it is considered more reactive than elemental hydrogen.

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

Identify the correct representation of reaction occurring during chloro-alkali process. 

  1. $2NaCl(l)+ 2H _2O(l) \rightarrow 2NaOH(l) + Cl _2(g) + H _2(g)$
  2. $2NaCl(s)+ 2H _2O(aq) \rightarrow 2NaOH(aq) + Cl _2(g) + H _2(g)$
  3. $2NaCl(aq)+ 2H _2O(l) \rightarrow 2NaOH(aq) + Cl _2(aq) + H _2(aq)$
  4. $2NaCl(aq)+ 2H _2O(l) \rightarrow 2NaOH(aq) + Cl _2(g) + H _2(g)$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chloro-alkali process is an industrial process for the electrolysis of sodium chloride. It is used to produce chlorine and sodium hydroxide. Aqueous sodium chloride or brine ina membrane cell.


At cathode: ${ 2H } _{ 2 }O+2{ e }^{ - }\rightarrow { H } _{ 2 }+{ 2OH }^{ - }$ 

At anode: $2{ Cl }^{ - }\rightarrow { Cl } _{ 2 }+2{ e }^{ - }$ 


$2NaCl(aq)+2{ H } _{ 2 }O\rightarrow { Cl } _{ 2 }(g)+{ H } _{ 2 }(g)+2NaOH(aq)$


Option $(D)$ suggests the correct reaction.

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

$Na _2CO _3.10H _2O \longrightarrow Na _2CO _3.H _2O$

The given reaction is an example of:

  1. efflorescent substance

  2. deliquescent substance

  3. hygroscopic substance

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

In this reaction water is being released. This type of substance is known as efflorescent substance.

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

Identify the correct representation of reaction occurring during chloralkali process.

  1. $2NaCl(l) + 2H _{2}O(l) \rightarrow 2NaOH(l) + Cl _{2}(g) + H _{2}(g)$
  2. $2NaCl(aq) + 2H _{2}O(aq) \rightarrow 2NaOH(aq) + Cl _{2}(g) + H _{2}(g)$
  3. $2NaCl(aq) + 2H _{2}O(l)\rightarrow 2NaOH(aq) + Cl _{2}(aq) + H _{2}(aq)$
  4. $2NaCl (aq) + 2H _{2}O (l)\rightarrow 2NaOH (aq) + Cl _{2}(g) + H _{2}(g)$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium chloride in water is a brine solution which gives sodium hydroxide in aqueous solution and hydrogen and chlorine gases. It is known as chloralkali process. It is an industrial process for the electyrolysis of sodium chloride. It is the technology which is used to produce chlorine and caustic soda(sodium hydroxide) on commercial scale.

Multiple choice chemistry petrochemicals and polymers petroleum properties of alkanes petroleum and natural gas rocks and minerals

The final product in the following reaction can be used as, $4CH _3-CH _2-Cl+4Na+Pb \rightarrow$

  1. anaesthatic

  2. narcotics

  3. analgesic

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

  • The final product of this reaction is $(CH _3CH _2) _4Pb$ [tetraethyl lead (TEL)].
$4CH _3-CH _2-Cl + 4Na + Pb \rightarrow (CH _3CH _2) _4Pb$
It is also used as an antiknocking agent in fuels for automobiles.

Multiple choice chemistry p- block elements-ii group 16 elements - general properties group 16 elements - trends in chemical properties group 16 elements

In which one of the following reactions, a 16 group element will get precipitated ?

  1. $ Na _2S _2O _3 + CI _2+H _2O \longrightarrow $
  2. $ Na _2SO _3 - CI _2+H _2O \longrightarrow $
  3. $ SO _2+2H _2O+CI _2 \longrightarrow $
  4. $ 2FeSO _4+H _2SO _4+CI _2 \longrightarrow $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the reaction of sodium thiosulfate with chlorine, sulfur is precipitated as a solid product.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

Nitrogen reaction with oxygen to form nitrogen (III) oxide.


What will be the volume ratio of the reactants and products of the given reaction?

  1. 2 : 3 : 2

  2. 2 : 3 : 4

  3. 1 : 3 : 2

  4. 2 : 1 : 2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$2 N _2 + 3 O _2 \rightarrow 2N _2 O _3$

reactants = $N _2 \, \& \, O _2$
Product = $N _2O _3$
Ratio are $2 : 3 : 2$ by law of constant proportions 
{stionchiometry coefficient) 


Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

3 volumes of hydrogen are required to combine with one volume of nitrogen to form 2 volumes of ammonia. When 1 mole of hydrogen is allowed to react with the mole of nitrogen, the two gases?

  1. Do not combine

  2. Combine and both the gases are used up completely

  3. 2/3 mole of nitrogen remains unreacted

  4. Some hydrogen remains uncombined
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$3H _2+N _2\rightarrow 3NH _3$
So 3 moles of hydrogen produced 1 mole of ammonia
1 mole hydrogen produces $X$ moles of ammonia
$X=\dfrac{1\times 1}{3}=\dfrac{1}{3}$ moles
Hence option $C$ is correct.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Following reactions take place during extraction of gold.
$4Au+8CN^-+2H _2O+O _2\rightarrow 4[Au(CN) _2]^-+4OH^-$
$2[Au(CN) _2]^-+Zn\rightarrow 2Au+[Zn(CN) _4]^{2-}$
Zinc in the extraction of gold acts as a/an:

  1. oxidising agent

  2. flux

  3. reducing agent

  4. decomposing agent
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
$4Au+8CN^-+2H _2O+O _2\longrightarrow 4[Au(CN) _2]^-+4OH^-$
$2[Au(CN) _2]^-+Zn\longrightarrow 2Au+[Zn(CN) _4]^{2-}$
                                 $0$                        $+2$
In the above reaction, Zinc is changing its states from $0$ to $+2$ so zinc is getting oxidized and it acts as reducing agent.
Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

$2Cu _{2}S + 3O _{2}(g)\xrightarrow {heat} {a} + {b}$

In the reaction above $a$ and $b$ are:

  1. $a = 2Cu _{2}O, b = 2SO _{2}$
  2. $a = 4CuO _{2}, b = 2SO _{3}$
  3. $a = 2CuO, b = 4SO _{2}$
  4. $a = 3CuS, b = 2SO _{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$2Cu _{2}S + 3O _{2} (g)\xrightarrow {\triangle} 2Cu _{2}O + 2SO _{2}(g)$
$2Cu _{2}O + Cu _{2}S\xrightarrow {\triangle} 6Cu(S) + SO _{2}(g)$.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

$Zn + NH _3 \quad\xrightarrow{\small{heat}} \quad ?$

  1. $ZnH _2 + N _2$
  2. $Zn _3N _2 + H _2$
  3. $Zn(NH _2) _2 + H _2$
  4. $[Zn(NH _3) _4]^{2+}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Zinc(II) ion forms complex ions readily.
Reaction of the process:
$Zn + xNH _3 \quad\xrightarrow{\small{red heat}} \quad Zn(NH _3) _x$
Where $x = 4$ to $6 $