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 further aspects of equilibria indicators and acid-base titration study of indicators properties of acids and bases

Dissociation of ${ CH } _{ 3 }COOH$ is suppressed by adding

  1. HCL
  2. ${ H } _{ 2 }{ SO } _{ 4 }$
  3. $CH _{ 3 }COONa\quad$

  4. Any of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

CH3COOH is a weak acid. Adding CH3COONa provides a common ion (CH3COO-), which shifts the equilibrium of the weak acid dissociation to the left, suppressing it according to Le Chatelier's principle.

Multiple choice chemistry phenomena around us changes and its classification types of changes classification of changes

Calcium carbide produces acetylene on reaction with water. Ethylene can be obtained by reduction of ${C} _{2}{H} _{2}$. Polythene is produced by polymerization of ${C} _{2}{H} _{4}$. Calculate the theoretical yield of polythene per kilogram of $Ca{C} _{2}$ :

  1. $0.6457kg$
  2. $0.4375kg$
  3. $0.5113kg$
  4. $0.3948kg$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Calcium carbide (CaC2) reacts with water to form acetylene (C2H2). Acetylene is reduced to ethylene (C2H4), which is then polymerized to form polythene (CH2CH2)n. Stoichiometric calculation shows 1 mole of CaC2 produces 1 mole of C2H2, which produces 1 mole of C2H4, resulting in 28g of ethylene units per 64g of CaC2.

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

$(CO+H _{2})+H _{2}\overset {673k,300atm,/Cr _{2}O _{3}-ZnO} {\rightarrow}$ 
The above shown reaction may by used for manufacture of:

  1. $HCHO$
  2. $CH _{3}COOH$
  3. $HCOOH$
  4. $CH _{3}OH$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Methanol is prepared on an industrial scale from a mixture of CO and H2. The mixture is subjected to 200atm pressure and passed over ZnO and Cr2O3 catalyst at 400 to 450 degrees celsius.

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

The reaction equation of the preparation of $HCl$ by synthesis is given by:

  1. $NaCl + H _2SO _4 \rightarrow NaHSO _4+HCl$
  2. $NaHSO _4+NaCl \rightarrow HCl+NaSO _4$
  3. $H _2+Cl _2 \rightarrow 2HCl$

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
In the chloralkali process, brine (mixture of sodium chloride and water) solution is electrolyzed producing chlorine (Cl$ _2$), sodium hydroxide, and hydrogen (H$ _2$):

2 NaCl + 2 H$ _2$O → Cl$ _2$ + 2 NaOH + H$ _2$

The pure chlorine gas can be combined with hydrogen to produce hydrogen chloride in the presence of UV light:

Cl$ _2$(g) + H$ _2$(g) → 2 HCl(g)

As the reaction is exothermic, the installation is called an HCl oven or HCl burner. The resulting hydrogen chloride gas is absorbed in deionized water, resulting in chemically pure hydrochloric acid. This reaction can give a very pure product, e.g. for use in the food industry.

Hence, the correct option is $\text{C}$
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 can be prepared by:

  1. $NaCl$ + $H _{2}SO _{4}$$\overset{420K}\rightarrow$
  2. $NaHSO _{4}$ + $NaCl$ $\overset{823K}\rightarrow$
  3. $NaNO _3$ + $H _{2}SO _{4}$ $\rightarrow$

  4. both (A) and (B).
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
HCl can be prepared by following :

$NaCl$ + $H _{2}SO _{4}$$\overset{420K}\rightarrow NaHSO _4+HCl$

$NaHSO _{4}$ + $NaCl$ $\overset{823K}\rightarrow Na _2SO _4+HCl$.

Hence option D is correct.
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

When phosphorous pentoxide is reacted with $HCl$ gas, products are:

  1. $POCl _3$
  2. $P _4O _{10}$
  3. $H _3PO _2$
  4. $HPO _3$
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Phosphorous pentoxide reacts with $HCl$ to form Phosphorous Oxychloride and metaphosphoric acid.


$2P _2O _5 + 3HCl \rightarrow POCl _3 + 3HPO _3$


Hence, $POCl _3$ and $HPO _3$ are correct.

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

In the Hydrolysis of ICl , the products are :

  1. HI +HCl

  2. HI +HOCl

  3. HCl+HOI

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

In the hydrolysis of ICl, the products are HCl + HOI.


$ICl+H _2O\rightarrow HCl+HOI$

During the hydrolysis of interhalogen compounds, oxyacid of less electronegative or large sized halogen is formed, and other halogen forms halogen acid. 

Thus, less electronegative iodine forms HOI and more electronegative chlorine forms HCl.

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

The standard formation reaction for aluminium oxide is $4Al(s) + 6O(g)\rightarrow 2Al _2O _3(s)$. This statement is false because:

  1. aluminium is not in its standard state

  2. the reaction should be written for one mole of Al
  3. The reaction is prevented by a thin film of $Al _2O _3$ formed on the surface of Al

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$2Al+3O _2\rightarrow Al _2O _3$

The enthalpy of the above reaction is enthalpy of formation as one mole of $Al _2O _3$ is forming from elemental aluminum and oxygen gas. 
Multiple choice bio-chemistry carbohydrate metabolism metabolism enzymes metabolism, cell respiration, and photosynthesis

Dark reaction is a

  1. Anabolic

  2. Catabolic

  3. Both A and B

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

The anabolic processes are the reactions in which the smaller organic molecules are used for the production of the large complex molecules. The carbon dioxide molecule is fixed in the dark reactions for the formation of the glucose molecule. Six molecules of CO$ _2$ are fixed to form one molecule of glucose in which the energy is stored. 

Thus, the correct answer is option A. 

Multiple choice aluminium patterns and properties of metals chemistry

${ aAl } _{ 2 }{ \left( { C } _{ 2 }{ O } _{ 4 } \right)  } _{ 3 }(s)\xrightarrow [  ]{ \Delta  } \quad { bAl } _{ 2 }{ O } _{ 3 }(s)+cCO(g)+d{ CO } _{ 2 }(g)$
According to the equation for the reaction represented above, what is the mole of $CO$ to ${CO} _{2}$ that is produced by the decomposition of aluminium oxalate?

  1. $1$ mole $CO$; $1$ mole of ${CO} _{2}$
  2. $1$ mole $CO$; $2$ moles of ${CO} _{2}$
  3. $1$ mole $CO$; $3$ moles of ${CO} _{2}$
  4. $2$ moles $CO$; $1$ mole of ${CO} _{2}$
  5. $3$ moles $CO$; $1$ mole of ${CO} _{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

${ Al } _{ 2 }{ ({ C } _{ 2 }{ O } _{ 4 }) } _{ 3 }(s)\xrightarrow { \Delta  } { Al } _{ 2 }{ O } _{ 3 }(s)+3CO(g)+3C{ O } _{ 2 }(g)$

According to the equation for the reaction represented above, what is the mole of $CO$ to $C{ O } _{ 2 }$ that is produced by the decomposition of aluminium oxalate is 1 mole of $C{ O }$ : 1 mole of $C{ O } _{ 2 }$

Multiple choice aluminium patterns and properties of metals chemistry

The dissolution of $Al(OH) _3$ by a solution of NaOH results in the formation of:

  1. $[Al(H _2O) _2(OH) _4]^-$
  2. $[Al(H _2O) _3(OH) _3]^+$
  3. $[Al(H _2O) _4(OH) _2]^+$
  4. $[Al(H _2O) _6(OH) _3]^-$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

1. $[Al(H _2O) _4(OH) _2]^+$

2. $Al(OH) _3$  dissolves in $NaOH$ solution to give $Al(OH)^{-4}$ ion which is supposed to have the octahedral complex species $[Al(OH) _4(H _2O) _2]^-$ in aqueous solution.

3. $Al(OH) _3 + NaOH(aq) \longrightarrow  [Al(OH) _4(H _2O) _2]^-(aq) + NaOH^+(aq)$

Multiple choice aluminium patterns and properties of metals chemistry

In the following reaction sequence,
$(A)+N _2 \xrightarrow { \triangle } (B) \xrightarrow {+H _2O} (C)+(D)$
white ppt. (C) is formed and gas (D) is evolved. White ppt. (C) dissolves in NaOH solution, while gas (D) gives white fumes in HCl. Thus, (A) is :

  1. B

  2. Al

  3. Ga

  4. C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$\underset{(A)}{2Al}+N _2 \rightarrow \underset{(B)}{2AlN}$
$\underset{(B)}{AlN}+3H _2O \rightarrow \underset{(C)}{Al(OH) _3}+\underset{(D)}{NH _3}$
Multiple choice aluminium patterns and properties of metals chemistry

$Al {4}C _{3} + 12H _{2}O \rightarrow 3CH _{4} + $______

  1. $4 Al (OH) _{3}$
  2. $4 Al (OH) _{2}$
  3. $3 Al (OH) _{4}$
  4. $3 Al (OH) _{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$ Al _4C _3 + 12H _2O \rightarrow 3CH _4 + 4Al(OH) _3$

When Aluminium carbide $Al _4C _3$ undergoes hydrolysis forms a methane along with a aluminium hydroxide as a product.