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 chemistry chemistry in everyday life common salt some useful compounds in everyday life salts and their properties

Which of the following imparts purple colour to glass?

  1. ${Cr} _{2}{O} _{3}$
  2. $Au{Cl} _{3}$
  3. ${Cu} _{2}O$
  4. $Mn{O} _{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 $MnO _2$which is black, is used to remove the green color from the glass and imparts purple tint to the glass. $Cr _2O _3$ imparts dark green colour, $Cu _2O$ produces a turquoise color, and $AuCl _3$ gives ruby red coloured glass.

Multiple choice chemistry chemistry in everyday life common salt some useful compounds in everyday life salts and their properties

Match the compounds /metal in $(X)$ with their uses in $(Y)$.

$X$ $Y$
$A.$ Liquid sodium metal $I.$ Breathing apparatus in submarine
$B.$ Potassium stearate $II.$ Explosive
$C.$ Potassium nitrate $III.$ Coolant in nuclear reaction
$D.$ Potassium superoxide $IV.$ Soft soap
  1. $A-I\, \quad\, B-III\, \quad\, C- II\, \quad\, D- IV$
  2. $A-III\, \quad\,B- IV\, \quad\,C- II\, \quad\, D- I$
  3. $A- II\, \quad\,B- I\, \quad\, C- III\, \quad\, D- IV$
  4. $A- IV\, \quad\, B- II\, \quad\, C- III\, \quad\,D- I$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

1. Liquid sodium metal is used as coolant in nuclear reaction
2. Potassium stearate is used in soft soap
3. Potassium nitrate is explosive
4. Potassium superoxide, which gives off oxygen as it absorbs carbon dioxide is used in Breathing apparatus in submarine

Multiple choice action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

Colourless solution of silver nitrate is taken in two test tubes A and B. Metal plates of copper and platinum are dipped into test tubes, A and B respectively. Content of test tubes ____________.

  1. B turns green

  2. B turns blue

  3. A turns blue

  4. A remains colourless
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In test tube A, displacement reaction takes place as copper being more reactive displaces silver from silver nitrate solution thus leading to the formation of copper nitrate which is blue in colour. The chemical reaction can be written as:
$Cu + Ag(NO _{3}) _{2} \rightarrow Cu(NO _{3}) _{2} + Ag$

Multiple choice chemistry aldehydes, ketones and carboxylic acids alkanoic acids nomenclature of carboxyl group nomenclature of carboxylic acids

Sodium salt of an organic acid 'X' produces effervescence with conc. $H _2SO _{4}$. 'X' reacts with the acidified aqueous $CaCl _2$ solution to give a white precipitate which decolourises acidic solution of $KMnO _4$. 'X' is 

  1. $C _6H _5COONa$
  2. $HCOONa$
  3. $CH _3COONa$
  4. $Na _2C _2O _4$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium oxalate (Na2C2O4) reacts with H2SO4 to release CO/CO2, and with CaCl2 to form calcium oxalate (white precipitate). Calcium oxalate is then oxidized by KMnO4 in acidic medium.

Multiple choice chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

Oxygen atom of ether is: 

  1. very active

  2. replaceable

  3. active

  4. comparatively inert
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Oxygen atom of ether is comparatively inert.

 $C-O-C$ linkage is quite stable. Under ordinary conditions, ethers are not acted upon by dilute acids, bases and most of the oxidizing and reducing agents. 

Hence correct answer is option D.
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

A metal salt solution forms a yellow precipitate with potassium chromate in acetic acid, a white precipitate with dilute sulphuric acid but does not give precipitate with sodium chloride or iodide. The white precipitate obtained when sodium carbonate is added to the metal salt solution will consist of:

  1. lead carbonate

  2. basic lead carbonate

  3. barium carbonate

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

Pb and Ba both give yellow ppt with $K _2CrO _4$ in acetic and white precipitate with dil. $H _2SO _4$. but lead salts give a precipitate with sodium chloride or iodide also whereas barium does not. It means given salt is barium salts and with sodium carbonate, it gives a white precipitate of barium carbonate.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

Beautiful colours of fireworks are produced by adding salts of various metals into the burning mixture. The firework colours of different metals are mentioned here. Pick the false one.

  1. Calcium gives a brick-red light

  2. Sodium gives a yellow light

  3. Copper gives a green light

  4. Strontium gives a blue light
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The Magical Colors of Fireworks
  • Red-strontium salts, lithium salts.
  • Orange- calcium salts.
  • Gold-incandescence of iron (with carbon), charcoal, or lampblack.
  • Yellow-sodium compounds.
  • White-white-hot metal, such as magnesium or aluminum.
  • Green-barium compounds + chlorine producer,copper.
  • Blue-copper compounds + chlorine producer.
  • Brick-red light-Calcium

Hence option D is wrong option.
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

Sparkling red colour after the blast of fire crackers is due to the presence of:

  1. sulphur

  2. sodium

  3. strontium

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

Firework colors come from the use of metal salts, packed in pellets called “stars.”Metal salts commonly used in firework displays include: strontium carbonate (red fireworks), calcium chloride (orange fireworks), sodium nitrate (yellow fireworks), barium chloride (green fireworks) and copper chloride (blue fireworks). 

Hence,Sparkling red colour after the blast of fire crackers is due to the presence of Strontium.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of sodium and potassium biological importance of elements biological importance of s block elements biological importance of magnesium and calcium

Select the correct statement with respect to sodium peroxide?

  1. It decolourises the $KMnO _4$ solution.
  2. On heating with oxygen at $450^0C$ and 300 atm pressure, it becomes paramagnetic.
  3. It is obtained along with sodium metal when sodium oxide is heated to a temperature more than $400^oC$.

  4. It gives both hydrogen peroxide and oxygen gas with water as well as with sulphuric acid.
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

(A) $2Mn{ O } _4^-(pink)+16H^++5O _2^{2-}\rightarrow 2Mn^{2+}+8H _2O+5O _2$.
(B) $Na _2O _2+O _2\xrightarrow [300 atm]{> 450^oC} 2NaO _2 ({ O } _2^-$ contains on unpaired electron in $\pi^*$ MO).
(C) $2Na _2O\xrightarrow {400^oC} Na _2O _2+2Na$.
(D) Gives only $H _2O _2$.

Multiple choice limestone uses of group 2 compounds group 2 industrial inorganic chemistry chemistry

Following compounds are used in fire-works :

  1. $LiNO _{3}$
  2. $BaCl _{2}$
  3. $(NH _{4}) _{2}Cr _{2}O _{7}$

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

All compounds are used in fire works.
$LiNO _{3}$ on ignition imparts crimson red,
                        $BaCl _{2} \rightarrow $ green
           $(NH _{4}) _{2}Cr _{2}O _{7}\rightarrow$ green.

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

A yellow precipitate obatined in II group of the equilibrium analysis was soluble in aq. $NaOH$ and insoluble in dil. $HNO _3$. This shows the presence of:

  1. $Tin$
  2. $Antimony$
  3. $Arsenic$
  4. $Cadmium$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In qualitative analysis, Tin (Sn) sulfides (SnS2) are soluble in yellow ammonium sulfide or NaOH, forming a soluble complex, and precipitate upon acidification with dil. HNO3 or HCl.

Multiple choice chemistry organic nitrogen compounds nitroarenes- preparation and properties nitro compounds types of organic reactions

Nitrobenzene is used for making aniline, an important chemical used in:

  1. the making of glue

  2. the dyeing industry

  3. the crimping of wool

  4. fast-drying varnish
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Its main use in dyeing industry is as a precursor to indigo, the blue of blue jeans.