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 chemistry in everyday life metal oxides and non metal oxides reactions of acids and bases properties of acids and bases

The reaction between dinitrogen trioxide and potassium hydroxide gives $KNO _2$.
$N _2O _3 + 2KOH  \rightarrow 2KNO _2 + H _2O$


What can we conclude about the nature of dinitrogen trioxide?

  1. It is acidic oxide

  2. It is basic oxide

  3. It is amphoteric oxide

  4. It is neutral oxide
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$N _2O _3 + 2KOH  \rightarrow 2KNO _2 + H _2O$

In the above reaction, we can see that dinitrogen trioxide is an acidic oxide, as $N _2O _3$ reacts with a base $(KOH)$ to form salt and water. This is the characteristic of acidic oxide.
Hence, option $A$ is correct.
Multiple choice chemistry chemistry in everyday life metal oxides and non metal oxides reactions of acids and bases properties of acids and bases

Which of the following represents the products obtained when $NaOH$ reacts with $NO _2$?

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

  3. Both of the above

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

When NaOH reacts with $NO _2$, the products obtained are $NaNO _2$ and $NaNO _3$
$2NaOH + 2NO _2 \rightarrow NaNO _2 + NaNO _3 + H _2O$

Multiple choice chemistry chemistry in everyday life metal oxides and non metal oxides reactions of acids and bases properties of acids and bases

$CuO+(X) \rightarrow CuSO _4+H _2O$ 

Here, $(X)$ is:

  1. $CuSO _4$
  2. $HCl$
  3. $H _2SO _4$
  4. $HNO _3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Acid and base react together, neutralize each other and form salt and water.

$Acid + Base \rightarrow Salt + water$
Here $CuO$ acts as a base and the salt formed is $CuSO _4$, along with formation of water $(H _2O)$.
Since the salt formed is $CuSO _4$, the reacting acid should be sulphate ion ($SO _4^{2-}$) donor, and water would not have been formed if $CuO\  and\  CuSO _4$  would have reacted together. Thus $H _2SO _4$ is the acid that will react with $CuO$ to give $CuSO _4\ and\ H _2O$. The reaction occurs as follows :-
$CuO+H _2SO _4\rightarrow CuSO _4+H _2O$
Hence, the correct answer is option (C).

Multiple choice chemistry chemistry in everyday life metal oxides and non metal oxides reactions of acids and bases properties of acids and bases

Chlorine is evolved by the action of:

  1. ${ H } _{ 2 }{ SO } _{ 4 } \ on\ NaCl$
  2. $HCl\ on\ { K } _{ 2 }{ SO } _{ 4 }$
  3. $HCl \ on\ KMN{ O } _{ 4 }$
  4. $HN{ O } _{ 3 }\ on\ KCl$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Option $(C)$ is the correct answer.
$Chlorine$ is evolved by the action of $\displaystyle HCl$ on $\displaystyle KMnO _4$
$\displaystyle 2KMnO _4+16HCl \rightarrow 2KCl + 2MnCl _2+8H _2O + 5Cl _2$

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

$   Mg        +          H _2O   \rightarrow $      

       (cold water)

  1. $MgO + H _2$
  2. $Mg _2O + H _2$
  3. $MgO + H _2O$

  4. The above reaction cannot occur
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Magnesium and zinc do not react with cold water. They form their respective oxides when reacted with hot water.
$   Mg        +          H _2O         \rightarrow           MgO         +       H _2  $
                            (hot water)

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

What does the pop sound indicate when sodium reacts with cold water?

  1. Release of oxygen

  2. Release of carbon dioxide

  3. Both A and B

  4. Release of hydrogen
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in this reaction. Hence, it is stored in kerosene. To test for the release of hydrogen gas, place a lighted splint over the reacting metal - if it "pops" then hydrogen is present.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

$2Fe(s) + 3H _2O(g)\rightarrow$

  1. $Fe _2O(s) + 3H _2(g)$
  2. $Fe _2O _3(s) + 3H _2(g)$
  3. $Fe _2O _3(s) + 3H _2O(g)$

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

Iron is less reactive than sodium, potassium, calcium, zinc and magnesium. It does not react with cold and hot water, but it reacts with steam to form magnetic oxides.
$ 2Fe(s) + 3H _2O(g) \rightarrow Fe _2O _3(s) + 3H _2(g) $

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

$Na+H _2O\rightarrow NaOH+H _2$ 


Balance the following reaction.

  1. $2Na+2H _2O\rightarrow 2NaOH+H _2$
  2. $Na+H _2O\rightarrow NaOH+2H _2$
  3. $2Na+H _2O\rightarrow NaOH+H _2$
  4. $Na+\dfrac12 H _2O\rightarrow NaOH+H _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium reacts with cold water and gives sodium hydroxide and hydrogen gas. The balanced chemical equation is

$\displaystyle 2Na + 2H _2O \rightarrow 2NaOH + H _2$

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Which requires catalyst

  1. $S+O _2 \rightarrow SO _2$
  2. $2SO _2+O _2 \rightarrow 2SO _3$
  3. $C+O _2 \rightarrow CO _2$

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

The oxidation of sulfur dioxide to sulfur trioxide (2SO2 + O2 -> 2SO3) is a slow reaction that industrially requires a catalyst, specifically vanadium pentoxide (V2O5) or platinum, to proceed at a practical rate in the Contact process. In contrast, combustion reactions like sulfur or carbon burning in oxygen occur readily without a specialized catalyst.