Chemistry

Chemical Reactions and Equations

684 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 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.

Multiple choice urea organic compounds with functional group containing nitrogen

First step of urea manufacture is $2NH _3 \ + \ CO _2 \rightleftharpoons X$
Compound $X$ is:

  1. $NH _2COONH _4$
  2. $NH _2COOH$
  3. $NH _4COOH$
  4. Both $A$ and $B$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The first is carbamate formation: the fast exothermic reaction of liquid ammonia with gaseous carbon dioxide at high temperature and pressure to form ammonium carbamate (${ H } _{ 2 }N-COO-N{ H } _{ 4 }$).

 $2N{ H } _{ 3 }+C{ O } _{ 2 }\rightleftharpoons { H } _{ 2 }N-COO-N{ H } _{ 4 }$

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

What is obtained when nitrobenzene is treated sequentially with (i) ${ NH } _{ 4 }Cl/Zn$ dust and (ii) ${ H } _{ 2 }{ SO } _{ 4 }/{ Na } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }$ ?

  1. Benzene

  2. Nitrosobenzene

  3. m-Chlorobenzene

  4. p-Chlorobenzene
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When Nitrobenzene first reacts with $NH _4Cl/Zn$ it forms phenyl hydroxylamine.

When this reacts with $H _2SO _4/ Na _2Cr _2O _7$ it gives Nitroso benzene as a product.

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

Benzene on reaction with conc. $HNO _{3}$ in presence of conc. $H _{2}SO _{4}$ followed by the treatment of $Cl _{2}$ in presence of $FeCl _{3}$, it gives :

  1. $2 - chloro - 1 - nitrobenzene$
  2. $1 - chloro - 3- nitrobenzene$
  3. $3 - chloro - 1- nitrobenzene$
  4. A mixture of $2 - chloro$ and $4 - chloro - 1 - nitrobenzene$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

3-Chloro-1-nitrobenzene
Nitro substituents have positive charge on the atom bonded to ring. So the like charges repel each other at ortho and para position as compared to meta substitution. So meta position is favored at 3 chloro in the ring.

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

When nitrobenzene is treated with $Br _{2}$ in presence of $FeBr _{3}$ the major product formed is m - bromonitrobensene. Statement which is related to obtain the m - isomer is:

  1. The electron density of meta carbon is more than that on ortho and para positions
  2. Loss of aromaticity when $Br^{+}$ attacks at the ortho and para positions and not at meta position
  3. Easier loss of $H^{+}$ to regain aromaticity from the meta position than from ortho and para positions

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

The exact influence of a given substituent is seen as its interactions with the delocalized positive charge on the benzonium intermediate generated by bonding to the electrophile at each of the three substitution sites. Nitro groups have a positive charge on the atom bonded to the aromatic ring. Like charges of two groups are destabilized by charge repulsion so meta-products predominate as compared to others.

Multiple choice chemistry occurrence of carbon compounds in nature importance of carbon covalent bonding in carbon compounds carbon and its forms

The reaction between carbon and oxygen can be represented as 
$C _{(s)}+O _{2(x)}\rightarrow CO _{2(g)}+heat$
In which of the following type(s), the above reaction can be classified?
I. Combustion reaction
II. Displacement reaction
III. Endothermic reaction
IV. Combination reaction

  1. (I) and (III)

  2. (I), (II) and (IV)

  3. (I) and (IV)

  4. (I) only
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$C _{(s)}+O _{2(g)}\rightarrow CO _{2(g)}+heat$
It is combination and combustion reaction.