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

Odor being given off can tell us that a ____________ has happened.

  1. Chemical Change

  2. Physical Change

  3. Condensation

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

The release of an odor is a common indicator that a chemical reaction has occurred, resulting in the production of new substances. Physical changes like evaporation or condensation typically do not produce new odors.

Multiple choice

CuO + H2SO4 --> ____ + ____

  1. CuSO4 + H2O

  2. FeSO4 + H2

  3. CuNO3 + H2O

  4. CuCl3 + H2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reaction between a metal oxide (CuO) and an acid (H2SO4) is a neutralization reaction that produces a salt (CuSO4) and water (H2O).

Multiple choice

NaOH + HCl --> ____ + ____

  1. NaCl + H2O

  2. KCl + H2

  3. KNO3 + H2O

  4. NaNO3 + H2O
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reaction between sodium hydroxide (a base) and hydrochloric acid (an acid) is a classic neutralization reaction resulting in sodium chloride (salt) and water.

Multiple choice some important compounds of magnesium and calcium the s-block elements chemistry

How is ${MgSO} _{4}$ produced from ${MgCO} _{3}$?

  1. ${MgCO} _{3}$${+}$ ${S}$
  2. ${MgCO} _{3}$${+}$ ${SO} _{2}$
  3. ${MgCO} _{3}$${+}$ ${SO} _{3}$
  4. ${MgCO} _{3}$ ${+}$ ${H} _{2}{SO} _{4}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Magnesium Sulphate is produced from Magnesium carbonate by reacting the carbonate with Sulphuric acid. The balanced equation can be written as-
${MgCO} _{3}$${+}$ ${H} _{2}{SO} _{4}$  ${=}$ ${MgSO} _{4}$ ${+}$ ${CO} _{2}$ ${+}$ ${H} _{2}{O}$

Multiple choice some important compounds of magnesium and calcium the s-block elements chemistry

The balanced chemical reaction for the manufacturing of superphosphate is:

  1. $Ca _3(PO _4) _2 +\ 2H _2SO _4 +\ 4H _2O \ \longrightarrow Ca(H _2PO _4) _2 \ + \ 2CaSO _4.2H _2O $
  2. $Ca _3(PO _4) _2 +\ H _2SO _4 +\ 4H _2O \ \longrightarrow Ca(H _2PO _4) _2 \ + \ CaSO _4.2H _2O $
  3. $Ca _3(PO _4) _2 +\ 2H _2SO _4 +\ 2H _2O \ \longrightarrow 2Ca(H _2PO _4) _2 \ + \ CaSO _4.2H _2O $
  4. $Ca _3(PO _4) _2 +\ 4H _2SO _4 +\ 2H _2O \ \longrightarrow Ca(H _2PO _4) _2 \ + \ 2CaSO _4.2H _2O $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A well powdered phosphate rock or bone ash mixed known quantity of concentrate sulphuric acid is introduced into a cast iron chamber provided with mechanical stirrer and two valves at bottom. Each valve opens in a big chamber called den. The mixture is stirred for 2 to 5 minutes and then dumped mechanically into one of the dens through the valve. The mass is kept in the den for about 24 hours.

${ Ca } _{ 3 }{ \left( P{ O } _{ 4 } \right)  } _{ 2 }+2{ H } _{ 2 }S{ O } _{ 4 }+4{ H } _{ 2 }O\longrightarrow Ca{ ({ H } _{ 2 }P{ O } _{ 4 }) } _{ 2 }+2CaS{ O } _{ 4 }.2{ H } _{ 2 }O+Heat$

A mixture of calcium sulphate and calcium dihydrogen phosphate is obtained .This mixture is called superphosphate.

Multiple choice some important compounds of magnesium and calcium the s-block elements chemistry

Which the correct chemical reaction among following?

  1. $MgSO _4 \xrightarrow {\Delta} MgO+SO _3$
  2. $Mg _NO _2 \rightarrow Mg _3+N _2$
  3. $MgCO _3 \rightarrow Mg+ CO+CO _2$
  4. $Mg+H _2O \rightarrow Mg(OH) _2+H _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Option $(A)$ is correct.

A). $MgSO _4 \xrightarrow {\Delta} MgO+SO _3$
C). $MgCO _3 \rightarrow Mg + CO _2$
D). $Mg+H _2O \rightarrow MgO + H _2$.
Magnesium reacts with water vapor to magnesium hydroxide and hydrogen gas

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

Matter undergoes a change. The changes are of two types : Physical and chemical change. A physical change is a change that involves only a change in the physical state of matter.
Its chemical properties remain the same. Usually increasing the temperature of applying pressure or both brings about a physical change. On reversing the condition, i.e., reducing the temperature or reducing the pressure or both, the original state of matter is restored. In other words, physical changes are reversible. A chemical change is a change that involves a change in the chemical composition of matter. A new substance is formed. In a chemical change, the chemical and physical properties of the substance is formed. In a chemical change, the chemical and physical properties of the substance formed will be different from the original substance. When zinc carbonate is heated and cooled, the change(s) that are observed are :

  1. Physical

  2. Nuclear changes

  3. First chemical and then physical

  4. First physical and then chemical
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

First zinc carbonate decomposes to give zinc oxide and $CO _2$ and zinc oxide appears yellow when hot and white when cold. Initially, zinc carbonate under goes chemical change. Cooling of zinc oxide a goes physical change, to change its colour from yellow to white.

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

When sugar is treated with sulphuric acid, we get a very pure form of:

  1. carbon

  2. oxygen

  3. water

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

(A) carbon

Concentrated sulphuric acid is a strong dehydrating agent. Sulphuric acid removes water from organic compounds; it is evident by its charring action on carbohydrates.
${C} _{12}{H} _{22}{O} _{11} \xrightarrow{\text{ conc. } {H} _{2}S{O} _{4}} 12C + 11{H} _{2}O$

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

${ C } _{ 12 }{ H } _{ 22 }{ O } _{ 11 }\longrightarrow 12C+{ 11H } _{ 2 }{ O }$ in presence of concentrated ${ H } _{ 2 }{ SO } _{ 4 }$.

Which of the following is obtained in the above reaction?

  1. Animal charcoal

  2. Sugar charcoal

  3. Coke

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

The dehydration of sucrose (C12H22O11) by concentrated sulfuric acid leaves behind a porous black mass of carbon known as sugar charcoal.