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 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 represents action of alkali on hydroxide?

  1. $ZnO+2NaOH\rightarrow Na _2ZnO _2+H _2O$
  2. $Zn\begin{pmatrix}OH\end{pmatrix} _2+2NaOH\rightarrow Na _2ZnO _2+2H _2O$
  3. $PbO+2NaOH\rightarrow Na _2PbO _2+2H _2O$

  4. Both A and C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Zn\begin{pmatrix}OH\end{pmatrix} _2+2NaOH\rightarrow Na _2ZnO _2+2H _2O$ represents action of alkali on hydroxide.

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 represents action of alkali on aluminium hydroxide?

  1. $Al\begin{pmatrix}OH\end{pmatrix} _3+NaOH\rightarrow NaAlO _2+2H _2O$
  2. $Al\begin{pmatrix}OH\end{pmatrix} _3+2KOH\rightarrow2KAlO _2+H _2O$
  3. $Al\begin{pmatrix}OH\end{pmatrix} _3+KOH\rightarrow KAlO _2+2H _2O$

  4. Both A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Aluminium hydroxide reacts with sodium hydroxide or potassium hydroxide to form the corresponding aluminate. Both Al(OH)3 + NaOH -> NaAlO2 + 2H2O and Al(OH)3 + KOH -> KAlO2 + 2H2O are valid representations of this reaction.

Multiple choice action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

Complete the following equation
$Pb\begin{pmatrix}OH\end{pmatrix} _2+NaOH\rightarrow$

  1. $Pb\begin{pmatrix}OH\end{pmatrix} _2+2NaOH\rightarrow Na _2PbO _2+2H _2O$
  2. $Pb\begin{pmatrix}OH\end{pmatrix} _2+NaOH\rightarrow2Na _2PbO _2+H _2O$
  3. $Pb\begin{pmatrix}OH\end{pmatrix} _2+2NaOH\rightarrow Na _2PbO _2+H _2O$
  4. $Pb\begin{pmatrix}OH\end{pmatrix} _2+NaOH\rightarrow Na _2PbO _2+2H _2O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$Pb\begin{pmatrix}OH\end{pmatrix} _2+2NaOH\rightarrow Na _2PbO _2+2H _2O$

Multiple choice chemistry chemical reactions of organic compounds uses of alcohols commercially important alcohols - ethanol some commercially important alcohols commercially important alcohols - methanol methanol

Balanced chemical equations for the following:
Monochloro ethane is hydrolysed with aqueous KOH :

  1. $CH _3CH _2Cl + KOH \rightarrow C _2H _5OH + HCl + K _2O$
  2. $CH _3CH _2Cl + KOH \rightarrow C _2H _3OH + KCl + H _2O$
  3. $CH _3CH _2Cl + KOH \rightarrow C _2H _3Cl + KOH + H _2$
  4. $CH _3CH _2Cl + KOH \rightarrow C _2H _5OH + KCl + H _2O$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Reaction:
$CH _3CH _2Cl + KOH \rightarrow  C _2H _5OH + KCl + H _2O$

when alkyl halide is hydrolysed by aq. KOH then corresponding alcohol is formed.

Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

An organic compound with molecular formula $C _4H _{10}O$ does not react with sodium . With excess of HI it gives only one type of alkyl halide. The compound is:

  1. $C _2H _5OC _2H _5$
  2. $CH _3{\underset{OCH _3}{\underset{|}{C}}}HCH _3$
  3. $CH _3CH _2CH _2OCH _3$
  4. $CH _3CH _2CH _2CH _2OH$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$C _4H _{10}O$ can have two structures :


$CH _3CH _2CH _2CH _2OH$   and  $C _2H _5OC _2H _5$.

Since it does not react with Na metal, it can not be an alcohol.

$C _2H _5OC _2H _5 + \underset{excess}HI\rightarrow 2C _2H _5I + H _2O$

Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

Which of the following products are not correctly matched in the given reactions?

  1. $C _2H _5OCH _3 + HBr \xrightarrow{373K} C _2H _5OH + CH _3Br$
  2. $C _2H _5OC _2H _5 + 2HI \rightarrow C _2H5I + C _2H _5OH$
  3. $C _2H _5OC _2H _5 + \overset{Excess}{HCl} \xrightarrow{Cold} [(C _2H _5) _2O^+H]Cl^-$
  4. $(CH _3) _3COC _2H _5 \xrightarrow{HI} (CH _3) _3CI + C _2H _5OH$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$C _2H _5-O-C _2H _5 +\underset{(excess)} 2HI \rightarrow 2C _2H _5I + H _2O$

Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

Anisole on reaction with chloromethane in presence of anhydrous $AlCl 3$ gives __________.

  1. o-methyl anisole and p-methoxy anisole

  2. p-methyl anisole and p-methoxy anisole

  3. o-methyl anisole and p-methyl anisole

  4. o-methoxy acetphenone and p-methoxy acetophenone .
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Anisole i.e. Phenyl methyl ether $CH _3OC _6H _5$ reaction with Chloromethane in the presence of anhy $AlCl _3$ electrophilic substitution reaction at ortho and para position w.r.t. methoxy group on benzene ring. It is called Friedel-craft alkylation reaction and represented as:
$C _6H _5OCH _3+ CH _3Cl \overset {AlCl _3}{\rightarrow} o-CH _3C _6H _5OCH _3+p-CH _3C _6H _5OCH _3$
Hence Anisole on reaction with chloromethane in presence of anhydrous AlCl3 gives o-methyl anisole and p-methyl anisole
Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

The number of monochloro derivaties of 2-methoxy propane are possible are: 

  1. 2

  2. 1

  3. 3

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

$\quad \quad \quad OC{ H } _{ 3 }\ \hspace{2mm} \quad \quad \quad |\ { H } _{ 3 }C-CH-C{ H } _{ 3 }$

2-methoxypropane
The number of monochloro derivatives are 3. They are:
1) $\quad \quad \hspace{2mm} \quad OC{ H } _{ 3 }\ \quad \quad \quad \quad |\ { H } _{ 2 }C-CH-C{ H } _{ 3 }\ \quad |\ \hspace{2mm} Cl$
2) $\quad \quad  \quad OC{ H } _{ 3 }\ \quad \hspace{2mm} \quad \quad |\ { H } _{ 3 }C-C-C{ H } _{ 3 }\ \quad \quad \hspace{2mm} \quad |\ \quad \quad \quad Cl$
3) $\quad \quad  \quad OC{ H } _{ 2 }-Cl\ \quad \hspace{2mm} \quad \quad |\ { H } _{ 3 }C-C-C{ H } _{ 3 } $

Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

The compound obtained by the reaction of diethyl ether with chlorine in the presence of sun light , is 

  1. Perchloro diethyl ether $H _5C _2-OC _2Cl _5$
  2. Perchloro diethyl ether $Cl _5C _2-O-C _2Cl _5$
  3. $\beta ,\beta '$ Dichloro diethyl ether $ClCH _2CH _2-O-CH _2CH _2Cl$
  4. $\alpha ,\alpha $ Dichloro diethyl ether
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Diethyl ether reacts with chlorine in the presence of sunlight to replace all hydrogen atoms with chlorine, resulting in perchloro diethyl ether.

Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

Diethyl ether can be decomposed with:

  1. $HI$
  2. $KMnO _4$
  3. $NaOH$
  4. $H _2O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

On heating with concentrated Hydrogen iodide $(HI)$ the C-O bond in ethers breaks forming alcohol and alkyl iodide. For example,

 ${ C } _{ 2 }{ H } _{ 5 }-O-{ C } _{ 2 }{ H } _{ 5 }+HI\longrightarrow { C } _{ 2 }{ H } _{ 5 }-I+{ C } _{ 2 }{ H } _{ 5 }OH$

 On boiling with excess of concentrated Hydrogen iodide $(HI)$, Alkyl iodide is formed.

${ C } _{ 2 }{ H } _{ 5 }-O-{ C } _{ 2 }{ H } _{ 5 }+2HI\longrightarrow 2{ C } _{ 2 }{ H } _{ 5 }-I+{ H } _{ 2 }O$

Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

Ethers are heated with excess of conc. hydrogen halide to give alkyl halide, then the reactivity order of hydrogen halide is :

  1. $HCl < HBr < HF$
  2. $HI > HBr > HCl $
  3. $HF < HCl < HBr $

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When $HX$ is in excess and reaction is carried out at high temperature. Iodine is a good nucleophile, displaces an alcohol molecule by $SN^2$ mechanism thus $HI>HBr>HCl$

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

In the reaction : $K _4[Fe(CN) _6] + K _2CO _3\rightarrow $ the product formed is :

  1. $FeCO _3$
  2. $KCN$
  3. $KFeCO _3$
  4. $K _3 [Fe(CN) _6]$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$K _4Fe(CN) _6+K _2CO _3\rightarrow 5KCN+KCNO+Fe+CO _2$.

In the above reaction only KCN is formed.

Hence, option B is correct.