Chemistry · Science General

Common Chemical Compounds and Reactions

1,197 Questions

Common chemical compounds and reactions questions test your knowledge of everyday chemicals, their formulas, and their interactions. Topics include properties of acids and bases, hard water chemistry, and compounds like baking soda and plaster of paris. This section is essential for general science preparation.

Acids and basesPlaster of parisHard water chemistryCommon chemical formulasEveryday chemical reactions

Common Chemical Compounds and Reactions Questions

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

Choose the correct answer from the alternatives given.
Dead burnt plaster is :

  1. $CaSO _4$
  2. $CaSO _4.\frac{1}{2}H _2O$
  3. $CaSO _4.H _2O$
  4. $CaSO _4.2H _2O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Anhydrous calcium sulphate, CaSO$ _4$ is known as 'dead burnt plaster'. It is formed by heating gypsum, $CaSO _4.2H _2O$ at a temperature above 393 K.

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

Gypsum is added to cement to:

  1. make the mixture more homogeneous

  2. improve the texture of cement

  3. make the cement light weight

  4. delay the setting time of cement
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The purpose of adding gypsum is only to slow down the process of setting of the cement so that it gets sufficiently hardened.

Hence, gypsum is added to cement to delay the setting time of cement.

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

Gypsum on heating to $300^{o}C$ gives:

  1. $CaSO _{4}2H _{2}O$
  2. $CaSO _{4}$
  3. $CaSO _{4}.\dfrac {1}{2}H _{2}O$
  4. $SO _{3}$ ans $CaO$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Here answer is option C

Gypsum- chemical formula ;$Ca{ SO } _{ 4 }\cdot 2{ H } _{ 2 }O$
When gypsum is heated at 300K, we get plaster of paris(calcium sulphate hemihydrated salt)
$Ca{ SO } _{ 4 }\cdot 2{ H } _{ 2 }O\rightarrow Ca{ SO } _{ 4 }\frac { 1 }{ 2 } { H } _{ 2 }O+\frac { 3 }{ 2 } { H } _{ 2 }O$
Hence calcium sulphate Hemihydrated salt $Ca{ SO } _{ 4 }\frac { 1 }{ 2 } { H } _{ 2 }O$ is produced after heating gypsum.

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

About $2.5\%$ gypsum $(CaSO _{4}.H _{2}O)$ is also added to cement as one of the consituents its function is to:

  1. Slow down the setting process to increase strength

  2. Speed the setting process to increase strength

  3. Absord moisture

  4. Make it anti-rusting
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gypsum is a mineral and is hydrated calcium sulphate in chemical form. Gypsum plays a very important role in controlling the rate of hardening of the cement. During the cement manufacturing process, upon the cooling of clinker, a small amount of gypsum is introduced during the final grinding process.Gypsum is added to control the “setting of cement”. If not added, the cement will set immediately after mixing of water leaving no time for concrete placing.
conclusion: hence the option (A) is correct

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

Dead burnt plaster is :

  1. ${ CaSO } _{ 4 }.{ 2H } _{ 2 }O$
  2. ${ MgSO } _{ 4 }.7{ H } _{ 2 }O$
  3. ${ CaSO } _{ 4 }.1/2{ H } _{ 2 }O$
  4. ${ CaSO } _{ 4 }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When Plaster of Paris $CaSO _4.\dfrac{1}{2}H _2O$ is heated above 393 K, its water of crystallisation is lost and anhydrous Calcium sulphate is left that is known as a dead burnt plaster.

Hence option D is correct answer.

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

Which of the following is called milk of magnesia?

  1. Suspension of ${\rm{Mg}}{\left( {{\rm{OH}}} \right) _{\rm{2}}}$
  2. Solution of ${\rm{MgS}}{{\rm{O}} _4}$
  3. Suspension of ${\rm{Mg}}$
  4. Solution of ${\rm{Mg}}{\left( {{\rm{HC}}{{\rm{O}} _3}} \right) _2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH)₂. It occurs in nature as the mineral brucite.

Milk of magnesia contains magnesium, which is a naturally occurring mineral. The human body requires magnesium to help many of its systems function properly, most notably the muscles and the nerves.

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

Name a compound which hardens on wetting with water.

  1. Calcium sulphate decahydrates

  2. Calcium sulphur hemihydrates

  3. Calcium sulphate

  4. Hydrated calcium sulphate
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The calcium compound that hardens on wetting with water is commonly known as Plaster of Paris (POP), chemically known as calcium sulphate hemihydrate having the formula $CaSO _4.1/2H _2O$

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

In paper industry, the chemical compound used for bleaching is :

  1. potassium sulphite

  2. calcium sulphate

  3. sulphuric acid

  4. calcium bisulfite
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A bleaching agent is a material that lightens or whitens a substrate through chemical reaction. The bleaching reactions usually involve oxidative or reductive processes that degrade color systems In paper industry, the chemical compound used for bleaching is calcium bisulphate. 

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

How can Calcium Sulphate be produced from $Ca _3(PO _4) _2$ ?

  1. Reacting with Sulphuric acid

  2. Reacting with Sulphur

  3. Reacting with Sulphur trioxide

  4. Reacting with Sulphur dioxide
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When Calcium Phosphate is treated with Sulphuric Acid, Calcium Sulphate is obtained as a precipitate along with the formation of Phosphoric Acid. The balanced equation can be written as-
$Ca _3(PO _4) _2$ $+$ $3H _2SO _4$ $=$ $2H _3PO _4$ $+$ $3CaSO _4$

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

What is the chemical formula of Gypsum?

  1. ${CaSO} _{4}$${.}$${5H} _{2}{O}$
  2. ${CaSO} _{4}$${.}$${7H} _{2}{O}$
  3. ${CaSO} _{4}$${.}$${2H} _{2}{O}$
  4. ${CaSO} _{4}$${.}$${9H} _{2}{O}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The chemical formula of Gypsum is ${CaSO} _{4}$${.}$${2H} _{2}{O}$. It contains two moles of water in it. It can also be said as Calcium Sulphate dihydrate.

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

Calcium Suphate can be produced by :

  1. ${ZnSO} _{4}$ ${+}$ ${CaO}$
  2. $FeSO _4 + CaO + H _2O$
  3. $MgSO _4 + CaSO _4$

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

Gypsum or Calcium sulphate can be produced from Zinc Sulphate by reacting Zinc Sulphate with Calcium Oxide or lime. We get a precipitate of Calcium Sulphate. The reaction can be written as-
${ZnSO} _{4}$ ${+}$ ${CaO}$ ${=}$ ${CaSO} _{4}$ ${+}$ ${ZnO}$