Chemistry · Science General

Common Chemical Compounds and Reactions

1,204 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 chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

The common ingredient required for making cement and glass is:

  1. washing soda

  2. baking soda

  3. limestone

  4. potash
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This glass is typically made using a wet batch process where the composition is primarily limestone, soda ash and silica. 

cement is made by heating limestone (calcium carbonate) with other materials (such as clay) to $1450 ^0C$ in a kiln

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Cement balls formed in its manufacturing is called:

  1. portland cement

  2. limestone

  3. clinkers

  4. alum
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the manufacture of Portland cement, clinker occurs as lumps or nodules, usually 3 millimetres (0.12 in) to 25 millimetres (0.98 in) in diameter, produced by sintering (fused together without melting to the point of liquefaction) limestone and alumino-silicate materials such as clay during the cement kiln stage.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Finely powdered clay and limestone mixed with water is introduced in:

  1. drum mixer

  2. rotary kiln

  3. pan-type granulator

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

A rotary kiln is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process. Materials produced using rotary kilns include cement, lime.

Cement kilns are used for the pyro-processing stage of manufacture of Portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Cement is the mixture of calcium __________ and calcium ___________, with small amount of gypsum salt.

  1. silicate, carbonate

  2. silicate, aluminate

  3. carbonate, oxide

  4. carbonate, aluminate
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
 Compound  Formula  Shorthand form  % by $weight$ 
 Tricalcium aluminate $Ca _3Al _2O _6$  $C _3A$  10 
 Tetracalcium   $Ca _4Al _2Fe _2O _{10}$ $C _4AF$  8 
Belite or dicalcium silicate  $Ca _2SiO _5$  $C _2S$  20 
Alite or tricalcium silicate  $Ca _3SiO _4$  $C _3S$  55 
Sodium oxide  $Na _2O$  $N $
Potassium oxide  $K _2O$  $K $ upto 2 
Gypsum  $CaSO _4.2H _2O$  $CSH _2$  5 

A cement is a binder, a substance used in construction that sets and hardens and can bind other materials together. The most important types of cement are used as a component in the production of mortar in masonry, and of concrete, which is a combination of cement and an aggregate to form a strong building material.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Gypsum is added to cement in order to:

  1. prolong hydration

  2. increase strength after hydration

  3. decrease heat of hydration

  4. reduce curing time
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gypsum is called the retarding agent of cement which is mainly used for regulating the setting time of cement and is an indispensable component. Without gypsum, cement clinker can condense immediately by mixing with water and release heat. The major reason is that C3A in the clinker can dissolve in water quickly to generate a kind of calcium aluminate hydrate, a clotting agent, which will destroy the normal use of cement. The retardation mechanism of gypsum is: when cement is hydrated, gypsum reacts with C3A quickly to generate calcium sulfoaluminate hydrate which deposits and forms a protection film on the cement particles to hinder the hydration of C3A and delay the setting time of cement.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

The process of formation of colloidal gel from calcium silicate and aluminates is:

  1. endothermic

  2. exothermic

  3. reversible
  4. both $B$ and $C$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The first stage of hydration is characterized by the rapid dissolution of clinker

${ Ca } _{ 3 }Si{ O } _{ 5 }+3{ H } _{ 2 }O\longrightarrow 3{ Ca }^{ 2+ }+4{ OH }^{ - }+{ H } _{ 2 }Si{ O } _{ 2 }^{ 4- }$

 immediately after the wetting of the clinker powder. In calorimetry measurements,  a large exothermic signal is measured due to wetting and dissolution of clinker. The wet clinker releases ions such as calcium, silicate and hydroxide to the solution. From the evolution of these ion concentrations the dissolution rate of clinker can be evaluated.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Portland cement consists essentially of compounds of:

  1. lime (calcium oxide, $CaO$)
  2. silica (silicon dioxide, $SiO _2$)
  3. alumina (aluminum oxide, $Al _2O _3$)

  4. all of them
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Limestone, sand, gypsum and coal dust are the materials required for the manufacture of cement. Lime, silica and alumina are contained in the above materials. Hence, the right answer is all of them.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Metal oxide that turns into cement upon roasting with clay is:

  1. $NO$
  2. $MgO$
  3. $BaO$
  4. $CaO$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Quicklime when roasted with clay forms cement. Calcium oxide is also called as quicklime. Hence, the metal oxide that forms clay on roasting with clay is $CaO$.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Which of the following is not present in portland cement?

  1. $Ca _3Al _2O _6$
  2. $Ca _3SiO _5$
  3. $Ca _2SiO _4$
  4. $Ca _3(PO _4) _2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Portland cement gets its strength from chemical reactions between the cement and water. The process is known as hydration.
  • Chemical composition of portland cements are-
  1.  $Ca _3Al _2O _6$
  2. $Ca _3SiO _5$
  3. $Ca _2SiO _4$
  4. $Na _2O$
  5. $K _2O$
  6. $CaSO _4.2H _2O$
  7. $Ca _4Al _2Fe _2O _{10}$
  • Hence option D is not present in portland cement.
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

When plaster of paris comes in contact with water it sets into a hard mass. The composition of the hard mass is:

  1. $CaSO _4.H _2O$
  2. $CaSO _4.Ca(OH) _2$
  3. $CaSO _4.2H _2O$
  4. $CaSO _4.2Ca(OH) _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When plaster of paris comes in contact with water it sets into a hard mass which is called gypsum. Its composition is $CaSO _4.2H _2O$

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Gypsum is added to Portland cement to:

  1. fasten the process of setting

  2. slow down the process of setting

  3. improve the colour of the cement

  4. increase the melting point of cement
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gypsum slows down the process of setting of the cement so that it gets sufficiently hardened.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Cement, the important building material is a mixture of oxides of several elements. Besides calcium, iron and sulphur, oxides of elements of which of the group (s) are present in the mixture?

  1. Group 2

  2. Groups 2, 13 and 14

  3. Groups 2 and 13

  4. Groups 2 and 14
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Cement is a mixture of calcium (present in group 2) and aluminium silicates (contains group 13 and 14 elements).
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Cement is a mixture of:

  1. calcium silicates

  2. calcium aluminates

  3. calcium silicates and aluminates

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cement is an important building material. It is also called Portland cement. Important ingredients of Portland cement are dicalcium silicate $\left( { Ca } _{ 2 }{ SiO } _{ 4 } \right) 26$%, tricalcium silicate $\left( { Ca } _{ 3 }{ SiO } _{ 5 } \right) 51$% and tricalcium aluminate$\left( { Ca } _{ 3 }{ Al } _{ 2 }{ O } _{ 6 } \right) 11$%.


Hence, cement is a mixture of calcium silicates and aluminates.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

Gypsum is added to clinker during cement manufacturing to:

  1. Decrease the rate of setting of cement

  2. Bind the particles of calcium silicate

  3. Facilitate the formation of colloidal gel

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During the cement manufacturing process, upon the cooling of the 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 water leaving no time for concrete placing. Hence, the addition of gypsum is required to decrease the rate of setting.


Hence, option $(A)$ is correct.

Multiple choice chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

Water is said to be permanently hard when it contains:

  1. chloride and sulphates of Mg and Ca

  2. bicarbonate of Na and K

  3. carbonate of Na and K

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Permanent hardness in water is caused by the presence of dissolved chlorides and sulfates of calcium and magnesium, which cannot be removed by boiling.