Chemistry

Chemical Compounds and Reactions

505 Questions

Chemical compounds and reactions involve understanding the properties, colors, and formation of various chemical substances. Questions focus on identifying precipitates, observing color changes during reactions, and naming common compounds. This topic is a fundamental part of the chemistry syllabus for competitive exams.

identifying precipitateschemical reaction colorscompound namingcolloidal particle propertiesacid base reactions

Chemical Compounds and Reactions Questions

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

Match metal ion (Part I) with colour (Part II) in presence of alizarin:


  Part I   Part II
I. ${ Sn }^{ 2+ }$ A. Blue
II. ${ Mg }^{ 2+ }$ B. Pink
III. ${ Al }^{ 3+ }$ C. Violet
IV. ${ Ba }^{ 2+ }$ D. Red

  1. I-A II-D III-C IV-B

  2. I-B II-A III-D IV-C

  3. I-C II-B III-A IV-D

  4. I-D II-C III-B IV-A
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$Alizarin$ is a typical mordant dye gives different colours with metal ions as some of them are given below: 

$Al^{3+} \Rightarrow Red$
$Sn^{2+}  \Rightarrow Pink$
$Ba^{2+} \Rightarrow Voilet$
$Mg^{2+} \Rightarrow Blue$

Option B is correct.
Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of:

  1. $CuCO _3$
  2. $CuSO _4$
  3. $CuCO _3.Cu(OH) _2$
  4. $CuO$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Copper reacts with $CO _2$ present in the air and forms a green coating on its surface due to the formation of basic copper carbonate.


$2Cu+O _2+CO _2+H _2O\rightarrow CuCO _3.Cu(OH) _2$

So, the correct option is $C$

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Mark the correct statement:
a) Damp air alone supplies both things needed for corrosion.
b) Ordinary water supplies both air and water for corrosion.
c) Moist air can't provide both things.

  1. a, b

  2. a, c

  3. b, c

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

Damp air supplies both the things needed for rusting of Iron. Ordinary water has some air dissolved in it. So, it can do the same.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of:

  1. $CuSO _{4}$
  2. $CuCO _{3}$
  3. $Cu(NO _{3}) _{2}$
  4. $CuO$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The green coat is due to the basic copper carbonate formation and is a mixture of copper carbonate and copper hydroxide $(CuCO _3$ and $Cu(OH) _2)$.

Multiple choice chemistry changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

The tarnishing of silver ornaments in atmosphere is due to:

  1. $Ag _{2}O$
  2. $Ag _{2}S$
  3. $Ag _{2}CO _{3}$
  4. $Ag _{2}SO _{4}$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

The tarnishing of silver ornaments in atmosphere is due to formation of silver oxide $Ag _{2}O$ and silver sulphide $Ag _{2}S$.

$2Ag\, +\, \displaystyle 
\frac{1}{2}{O _{2}}\, \rightarrow\, Ag _{2}O$

$2Ag\, +\, H _{2}S\, \rightarrow\, Ag _{2}S\, +\, H _{2}$

Hence, option A and B are correct.

Multiple choice chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

A dilute mineral acid, which forms a white precipitate when treated with barium chloride solution is :

  1. Dilute nitric acid

  2. Dilute sulphuric acid

  3. Dilute hydrochloric acid

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

Dilute sulphuric acid is dilute mineral acid which forms a white precipitate when treated with barium chloride solution.

BaCl2 + H2SO4 ———— BaSO4 + HCl

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Iron filings were added to a solution of copper sulphate. After 10 minutes, it was observed that the blue colour of the solution changes and a layer gets deposited on iron filings. The colour of the solution and that of the coating would, respectively, be -

  1. Yellow and green

  2. Brown and blue

  3. Red and greenish-blue

  4. Green and reddish-brown
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Fe+CuSO _4\rightarrow FeSO _4+Cu$
                             Green     Reddish brown
Solution becomes green and reddish brown coating of copper is formed.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which of the following gives black precipitate with $H _{2}S$ ?

  1. Cupric chloride

  2. Cadmium chloride

  3. Zinc chloride

  4. Ferric chloride
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Iron from blast furnace is Pig Iron. It is intermediate to form Wrought Iron or Cast Iron. It is the first product from Blast Furnace. After applying some chemical reactions, pure iron will come.

Multiple choice chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

$NH _4CI(s)$ is heated in a test tube, vapours are brought in contact with red litmus paper, which changes to blue and then to red. it is because of : 

  1. formation of $NH _4OH$ and $HCI$
  2. formation of $NH _3$ and $HCI$
  3. greater diffusion of $NH _3$ than $HCI$
  4. grater diffusion of $HCI$ than $NH _3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$NH _4Cl\xrightarrow{\Delta} NH _3+HCl$
First HCl reacts with red litmus and converts it into blue but as diffusion of ammonia is high so after that ammonia reacts with blue litmus and converts back to red.

Multiple choice chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

The wrong statements about $\displaystyle NH _{3}$ is :

  1. it is oxidised with oxygen at $\displaystyle 700^{\circ}C$ in the presence of platinum

  2. it gives black precipitate with calomel
  3. it can be dried by $\displaystyle P _{2}O _{5},\ H _{2}SO _{4}\, $and$\, CaCl _{2}$

  4. it gives white fumes with HCI
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
$NH _3$ is oxidised to nitric oxide and water with oxygen at $700^oC $ in the presence of platinum.
Aqueous ammonia reacts with calomel $Hg _2Cl _2$ to produce metallic mercury, a black precipitate. 
$CaO$ calcium oxide is used for drying of ammonia. Because $CaO$ being basic in nature does not react with $NH _3$ while $P _2O _5, $ conc. $H _2SO _4 \ $and$ \ CaCl _2$ reacts with it.
$CaO + H _2O + NH _3 \rightarrow NH _3 + Ca(OH) _2$
$CaCl _2 + 8NH _3 \rightarrow CaCl _2.8NH _3$
$P _2O _5 + 3H _2O + 6NH _3 \rightarrow 2(NH _4) _3PO _4$
$H _2SO _4 + NH _3 \rightarrow (NH _4) _2SO _4$
$NH _3$ gives White fumes of $NH _4Cl$ with $HCl$.
Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

Name the radiation which can be detected by a solution of silver chloride. 

  1. X-ray radiation

  2. ultraviolet radiation

  3. infrared radiation

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

Johann Ritter decided to place silver chloride in the area just beyond the violet end of the spectrum, in a region where no sunlight was visible. To his amazement, he saw that the silver chloride displayed an intense reaction well beyond the violet end of the spectrum, where no visible light could be seen. This showed for the first time that an invisible form of light existed beyond the violet end of the spectrum. This new type of light, which Ritter called Chemical Rays, later became known as ultraviolet light or ultraviolet radiation (the word ultra means beyond).
Hence, the radiation which can be detected by a solution of silver chloride is Ultraviolet radiation.

Multiple choice

What is the importance of data standardization in Chemical Information Science?

  1. It ensures consistent representation of chemical data

  2. It facilitates the integration of chemical data from different sources

  3. It enables the development of interoperable chemical information systems

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

Data standardization is important in Chemical Information Science as it ensures consistent representation of chemical data, facilitates the integration of chemical data from different sources, and enables the development of interoperable chemical information systems.

Multiple choice

Which of the following is a common functional group found in many drugs?

  1. Amine

  2. Carboxylic acid

  3. Alkene

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

Amines are a common functional group found in many drugs due to their ability to form hydrogen bonds and interact with biological molecules.

Multiple choice

What is the name of the chemical compound that is commonly known as ammonia?

  1. NH3

  2. NO2

  3. SO2

  4. CO2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ammonia is the chemical compound that is commonly known as NH3. It is a colorless, pungent gas that is used in the manufacture of fertilizers, explosives, and plastics.