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 bio-chemistry immunity and blood groups blood group blood groups and compatibility advance blood groups and transfusion compatibility of blood groups

Which of the following chemicals can be used as anticoagulant?

  1. Sodium chloride

  2. Sodium citrate

  3. Sodium nitrate

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

Sodium citrate is a common anticoagulant used in blood collection because it chelates calcium ions, which are necessary for the blood clotting cascade.

Multiple choice bio-chemistry immunity and blood groups blood group blood groups and compatibility advance blood groups and transfusion compatibility of blood groups

Which one is the common anticoagulant used for preserving blood?

  1. Sodium hydroxide

  2. Sodium chloride

  3. Sodium oxalate

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

Sodium oxalate and sodium citrate are common anticoagulants used in blood collection tubes because they bind calcium ions, which are essential for the blood clotting cascade.

Multiple choice evs - i constituents of food minerals in our diets types of nutrients nutrients and deficiency

Among the below given minerals, Potassium Chloride is extracted from
a) Sylvite
b) Carnallite
c) Potash

  1. Only a

  2. Only a and b

  3. Only b and c

  4. All a,b and c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Potassium Chloride can be extracted from-

$a.$ Sylvite (Potassium Chloride in natural mineral form)
$b.$ Carnallite $(KCl\cdot MgCl _2\cdot 6H _2O)$
$c.$ Potash (rich in potassium chloride)

Multiple choice chemistry chemical changes electrochemical reactions electrolysis and its applications electrolytic cells and electrolysis

In Down's process for the manufacture of sodium, $CaCl _2$ is added to:

  1. decrease the melting point

  2. increase the melting point

  3. decrease the interionic interactions

  4. increase the interionic interactions
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$CaCl _2$ is added to lower the melting point from 1080 K (melting point of NaCl) to 850 K. This is due to following reasons.
a. At such high temperature, it is very difficult to maintain Na in the molten state during electrolysis.
b. Moreover, Na is voltile at this temperature and a part of it would vapourize.
c. Molten Na, gets dispersed in molten NaCl to form metallic fog at high temperature.
d. Both Na and $Cl _2$ produced in the electrolysis have a corrosive action on the vessel used.
The over all reactions nare as follows :
At cathode : $Na^{\oplus} + e^{-} \rightarrow Na$
At anode : $Cl^{\ominus} \rightarrow \displaystyle \frac{1}{2} Cl _2 + e^{-}$

Multiple choice chemistry chemical changes electrochemical reactions electrolysis and its applications electrolytic cells and electrolysis

Which of the following aqueous solutions remain alkaline after electrolysis ?

  1. $CH _{3}COONa$
  2. $KNO _{3}$
  3. $NaCl$
  4. $LiF$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

a. Reduction potential of $H _{2}O\, >$ Reduction potential of $Na^{\oplus}$
Hence, 
Cathode : $2H _{2}O\, +\, 2e^{-}\, \rightarrow\, 2 \overset{\ominus}{O}H\, +\,\begin{matrix} H _{2}\ (solution\, is\, basic)\end{matrix}$

Anode : $CH _{3}\, COO^{\ominus}\, \overset{Kolbe's\, electrolysis}{\rightarrow}\, C _{2}H _{6}\, (Ethane)\, +\, 2CO _{2}$

b. $K^{\oplus}$ does not undergo reduction but reduction of $H _{2}O$ occurs to give $\overset{\ominus}{O}\, H$ ion and $H _{2}(g)$.
Similarly, $NO^{\ominus} _{3}$ ion does not undergo oxidation but oxidation of $H _{2}O$ occurs to give $H^{\oplus}$ ions and $O _{2}(g)$. 
$H^{\oplus}$ and $\overset {\ominus}{O}H$ ions get neutralised and pH = 7 (neutral solution).
c. $Na^{\oplus}$ ions do not undergo reduction but reduction of $H _{2}O$ occurs to give $\overset{\ominus}{O}H$ ions and $H _{2}(g)$. (Hence, solution is basic). $Cl^{\ominus}$ undergoes oxidation to give $Cl _{2}(g)$. 
d. Same explanation as in (b).

Hence, options A and C are correct.

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 reaction of water with slaked lime is studied by ________ .

  1. putting slaked lime into water taken in a test tube

  2. putting a lot of water into slaked lime.

  3. sprinkling a little water on slaked lime.

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

The reaction of water with calcium oxide (quicklime) to form slaked lime is highly exothermic. To study it safely, one typically adds small amounts of water to the lime or vice-versa under controlled conditions, but the standard laboratory demonstration involves adding water to the solid.

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 function of quick lime mixture is to:

  1. Absorb moisture present in soda lime

  2. increase the efficiency of soda lime

  3. Increase the pH of soda lime

  4. Take part in reaction with NaOH
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$CaO$ is a compound that absorbs moisture easily and rapidly.

So it is used in some lime. It also adsorbs $CO _2$
Hence option A is the correct answer.

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

Setting of plaster of paris involves:

  1. oxidation with atmospheric oxygen
  2. combination with atmospheric $CO _{2}$

  3. dehydration

  4. hydration to yield another hydrate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

On hydration of Plaster of Paris, converts into Gypsum.
$\underset {\text {Plaster of Paris}}{CaSO _{4} \cdot \dfrac {1}{2} H _{2}O} + \dfrac {3}{2} H _{2}O\rightarrow \underset {Gypsum}{CaSO _{4}\cdot 2H _{2}O}$

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

Identify which contributes for strengthening of lime mortar structures and contributes for weakening of RCC structures the factor(s).

  1. Usage of water containing dissolved salts

  2. Addition of lime
  3. Absorption of $CO _2$ from atmospheric air

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

Absorption of $CO _{2}$ from atmospheric air contributes for strengthening for lime mortar structure as when atmospheric $CO _{2}$ combines with hydrated lime, limestone is formed which is a solid.

RCC structures are plain cement concrete reinforced with steel bars. Generally, the pH of new concrete is 12-13 which surrounds embedded reinforcement with the passivating layer of highly alkaline cement protecting reinforcement against corrosion. When atmospheric $CO _{2}$ comes in contact with the RCC structure it gets corroded and production of $CaCO _{3}$ occurs due to which alkalinity of the concrete decreases and the steel reinforcement is then susceptible to corrosion. This is how RCC structure gets weaken in the presence of atmospheric $CO _{2}$

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

A mixture of slaked lime, sand and water is known as ______.

  1. portland cement

  2. lime mortar

  3. milk of lime

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

Portland cement contains calcium oxide (quicklime) and clay (silica along with small quantity of alumina, magnesia and ferric oxide).

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

Plaster of paris hardens by :

  1. giving $CO _{2}$

  2. changing into carbonate

  3. uniting with water

  4. giving out water
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
$\underset{\text{plaster of paris}}{CaSO _4.1/2H _2O} \xrightarrow[\text{setting}]{H _2O} \underset{\begin{matrix}\text{gypsum}\\\text{othorhombic}\\\text{dihydrate}\end{matrix}}{CaSO _4.2H _2O} \xleftarrow[\text{hardening}]{} \underset{\begin{matrix} \text{gypsum} \\\text{monoclinic dihydrate}\end{matrix}}{CaSO _4.2H _2O}$

Plaster of paris absorbs water to form dihydrate, which sets to form a hard unified mass.
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

Important constituent of Portland and high alumina cements is?

  1. $Ca _{3}Al _{2}O _{6}$
  2. $CaSiO _{3}$
  3. $CaSO _{4}.2 H _{2}O$
  4. $Fe _{2}CO _{3}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Portland cement essentially consists of compounds of lime(Calcium Oxide CaO) mixed with silica(Silicon dioxide ) and Alumina(Aluminium Oxide).

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

Plaster of paris in contact with water sets to a hard mass whose composition is :

  1. $CaSO _{4}$
  2. $CaSO _{4}.H _{2}O$
  3. $CaSO _{4}.2H _{2}O$
  4. $CaSO _{4}.Ca(OH) _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On mixing with water, plaster of paris takes up water of crystallization to form orthorhombic calcium sulphate dihydrate. This sets to a hard mass which is monoclinic calcium sulphate dihydrate or gypsum. This is the final product of setting of plaster of paris. Its composition is $CaSO _4 \cdot 2H _2O $.