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 evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Which among the following is associated with iron sulphide ?

  1. Element

  2. Mixture

  3. Compound

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

Iron(II) sulfide or ferrous sulfide is a chemical compound with the formula $FeS$. Iron sulfides are often non-stoichiometric. powdered iron sulfide is pyrophoric (ignites spontaneously in air).

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

Which of the following is the preferred electrolyte for silver plating?

  1. $AgCl+HCl$
  2. $Ag{NO} _{3}+H{NO} _{3}$
  3. ${Ag} _{2}{SO} _{4}$
  4. $AgCN+NaCN$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Silver plating is an electroplating process utilizing an electrolyte containing silver cyanide solution and some free cyanide ions and operating at pH value not less than $8$. Free cyanide prevents precipitation of silver cyanide salt from the solution, provides electrical conductivity of the electrolyte and helps in the dissolution of silver anodes.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

 In the silver plating of copper, $K[Ag(CN) _2]$ is used instead of $AgNO _3$. The reason is:

  1. a thin layer of Ag is formed on Cu

  2. more voltage requirement
  3. $Ag^+$ ions are completely removed from solution
  4. less availability of $Ag^+$ ions, as Cu cannot displace Ag from $[Ag(CN) _2]^-$ ion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Option D is correct 

less avaibality of $Ag+$ions as, $Cu$ cannot displace $Ag$ from $[Ag(CN) _2]$
$Cu$ can replace $Ag$ in $AgNO _3$. But In coordination compound $Ag$ can't be replaced.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

A solution of ${ AgNO } _{ 3 }$ is a good electrolyte but is not used for electroplating an article with silver because :

  1. rapid deposition of silver takes place resulting in uneven coating

  2. slow deposition of silver takes place resulting in uneven coating

  3. poor conduction of silver

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

A solution of $AgNO _3$ is a good electrolyte but is not used for electroplating an article with silver because it undergoes very fast redox process and electroplating done through this process is not uniform.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Bleaching powder and bleach solution are produced on a large scale and is used in several house-hold products. The effectiveness of bleach solution is often measured by iodometry. Bleaching powder contains a salt of an oxoacid as one of its components. The anhydride of that oxoacid is:

  1. $Cl _{2}O$
  2. $Cl _{2}O _{7}$
  3. $ClO _{2}$
  4. $Cl _{2}O _{6}$
  5. $Cl _2O _3$
  6. $Cl _2O _5$
  7. $Cl _3O _9$
  8. $Cl _3O _5$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bleaching powder is $Ca(OCl)Cl$.


So, bleaching powder contains a salt of $HOCl$.

$Cl _2O$ is an anhydride of $HOCl$.

$Cl _2O+H _2O\Rightarrow 2HOCl$.

Hence, option A is correct.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Select correct statements (s):

  1. $ClO _2\ and \ Cl _2O$ are used as bleaching agents for paper pulp and textiles.
  2. $OCl^-$ salts are used as detergents.
  3. $OCl^-$ disproportionates in alkaline medium.
  4. $BrO^- _3$ is oxidised to $Br^-$ in acidic medium.
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

A. The oxides of chlorine such as $ClO _2$  and $Cl _2O$ are used as bleaching agents for paper pulp and textiles. Thus, the option A is correct.

B. $OCl^-$ salts cannot be used as detergents. Thus, the option B is incorrect.

C. In alkaline medium, $OCl^-$ disproportionates. $3ClO^- \xrightarrow {\Delta} 2Cl^-+ClO _3^-$. Thus, the option C is correct.

D. In acidic medium, $BrO _3^-$ is reduced to $Br^-$. $KBrO _3 + 3H _2SO _3 \rightarrow KBr + 3H _2SO _4$ Thus, the option D is incorrect.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Number of valence electrons present in atoms of $HClO _{4},HClO _{3},HClO _{2}$ respectively are :

  1. $32,26,20$
  2. $26,20,14$
  3. $36,30,24$
  4. $28,22,16$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Number of valence electrons present in atoms of $HClO _{4},HClO _{3},HClO _{2}$ are32,26,20 respectively.
Number of valence electrons present in atoms of  $HClO _{4}$ are $1+7+4(6)=32$
Number of valence electrons present in atoms of  $HClO _{3}$ are $1+7+3(6)=26$
Number of valence electrons present in atoms of  $HClO _{2}$ are $1+7+2(6)=20$

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Bleaching action of $CaOCl _2$ is due to :

  1. Nascent oxygen
  2. $Ca$
  3. $Cl$
  4. $HCl$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Calcium oxychloride ($CaOCl _2$) is known as bleaching powder. When it is treated with excess of dilute acids, chlorine is evovled which is responsible for the bleaching action of bleaching powder. Due to the evolution of nacent oxygen, it acts an an oxidising and bleaching agent.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Bleaching powder loses its power on keeping for long time because :

  1. it changes to calcium hypochlorite.

  2. it changes to calcium chloride and calcium hydroxide.

  3. it absorbs moisture.

  4. it changes to calcium carbonate and chlorine.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Bleaching powder reacts with carbon dioxide in air to give chlorine and calcium carbonate.

$2Ca(ClO) _2 + 2CO _2 \rightarrow 2CaCO _3 + 2Cl _2 + O _2$

Multiple choice chemistry occurrence of carbon compounds in nature substances, objects and energy alternative fuels and energy sources alternative sources of energy

A liquid fuel used in homes is:

  1. Water

  2. LPG

  3. CNG

  4. Cooking oil
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cooking oil or Vegetable oil can be used as an alternative fuel in diesel engines and in heating oil burners. When vegetable oil is used directly as a fuel, in either modified or unmodified equipment, it is referred to as straight vegetable oil (SVO) or pure plant oil (PPO). Conventional diesel engines can be modified to help ensure that the viscosity of the vegetable oil is low enough to allow proper atomization of the fuel. This prevents incomplete combustion, which would damage the engine by causing a build-up of carbon. Straight vegetable oil can also be blended with conventional diesel or processed into biodiesel or bioliquids for use under a wider range of conditions.

Hence, the correct option is $D$

Multiple choice chemistry occurrence of carbon compounds in nature substances, objects and energy alternative fuels and energy sources alternative sources of energy

Coal is processed in industries to get some useful products. Which of the following is not obtained from coal?

  1. Coke

  2. Coal tar

  3. Coal gas

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

CNG is made by compressing natural gas which is mainly composed of methane, to less than 1 percent of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 MPa, usually in cylindrical or spherical shapes.

Multiple choice chemistry rocks and minerals coal and its products study of coal coal

The characteristic of coal is ___________.

  1. toughness

  2. black in colour

  3. porous nature

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

Since coal is a form of sedimentary rock, it's is hard and porous. It is black due to its prime composition of carbon, compressed at high temperature and pressure.

Multiple choice chemistry rocks and minerals coal and its products study of coal coal

Which of the following is not characteristic of coke?

  1. Hard

  2. Porous

  3. High carbon content

  4. Soft
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Coke is a tough, porous and black substance. It is the purest form of carbon. Coke is used in the homes for cooking, heating and in industries, for manufacturing of steel and extraction of many metals. It is also used in thermal power plants to produce electricity.
Hence, option D is the correct option