Chemistry

Chemical Compounds and Reactions

329 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 substances in common use percent composition water of crystallisation percentage composition and empirical formula

Copper sulphate pentahydrate is commonly called as____, whereas ferrous sulphate heptahydrate is commonly called as _____ .

  1. white vitriol, blue vitriol

  2. green vitriol, blue vitriol

  3. blue vitriol, green vitriol

  4. blue vitriol, white vitriol
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Copper sulphate pentahydrate ($CuSO _4.5H _2O$) commonly known as blue vitrol contains 5 water molecules which gives it a blue color. Similarly, the green color of ferrous sulphate heptahydrate ($FeSO _4.7H _2O$) is due to 7 molecules water present in it. This water is responsible for the geometric shape and color of the crystals.

Multiple choice aluminium patterns and properties of metals chemistry

Which of the following compounds can make clothes fire proof ?

  1. $FeSO _{4}$
  2. $Al _{2}(SO _{4}) _{3}$
  3. $Cu _{2}SO _{4}$
  4. $MgSO _{4}.7H _{2}O$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Al _2(SO _4) _3$ used to make fire proof clothes.

Multiple choice aluminium patterns and properties of metals chemistry

The hydroxide, which is soluble in excess of sodium hydroxide is:

  1. $Fe(OH) _{3}$
  2. $Cu(OH) _{2}$
  3. $Cr(OH) _{3}$
  4. $Al(OH) _{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Aluminium hydroxide is insoluble in $H _2O$ but it is soluble in strong acids and strong bases. This is because of $Al(OH) _3$ its amphoteric nature.

$Al(OH) _3 + NaOH \rightarrow Na[Al(OH) _4]$

Multiple choice aluminium patterns and properties of metals chemistry

The incorrect statement among the following is:

  1. Bleaching powder is used as a germicide

  2. Chlorine is used in the preparation of

    insecticides like DDT.

  3. Fluorine is used in Rocket fuels
  4. $Na _{3}AlF _{3}$ is not a insecticide
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Na _{3}AlF _{3}$ is used as a insecticide
So D is false

Multiple choice carbon tetrachloride ddt preparation of haloalkanes halogen derivatives

What happens when $C{Cl} _{4}$ is treated with $Ag{NO} _{3}$ solution?

  1. ${NO} _{2}$ is evolved
  2. A white precipitate of $AgCl$ is formed
  3. $C{Cl} _{4}$ will dissolve in $Ag{NO} _{3}$ solution

  4. No reaction
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$C{Cl} _{4}$ is a covalent compound, so it does not react with $Ag{NO} _{3}$

Multiple choice salts salts and their classification acids, bases and salts chemistry

When the aqueous solution of silver nitrate and sodium chloride are mixed, a________ precipitate is immediately formed.

  1. yellow

  2. white

  3. red

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

When silver nitrate $(AgNO _3)$ reacts with sodium chloride $(NaCl)$ a white precipitate of silver chloride $(AgCl)$ is formed which is highly insoluble in water, along with formation of sodium nitrate $(NaNO _3)$.

Since $(AgCl)$ is insoluble in water it will precipitate out and $(NaNO _3)$ is soluble in water so it will remain dissolved in the mixture. This reaction is an example of double displacement reaction and it occurs as follows:-
$AgNO _3\ +\ NaCl \rightarrow AgCl\ +\ NaNO _3 $
Hence, the correct answer is the option (B).

Multiple choice salts salts and their classification acids, bases and salts chemistry

A and B are two salts. A with dil. HCI and A and B with conc. ${H _2}S{O _4}$react to give reddish brown vapours, hence A and B respectively are:

  1. $NaN{O _3},NaBr$
  2. $NaBr,NaN{O _3}$
  3. $NaBr,NaN{O _2}$
  4. $NaN{O _{2,}}NaBr$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bromide salts (NaBr) react with conc. H2SO4 to produce reddish-brown bromine vapors. Nitrates (NaNO3) react with conc. H2SO4 to produce reddish-brown NO2 gas upon heating. Since A reacts with dil. HCl, it must be the bromide (as nitrates do not react with dil. HCl).

Multiple choice salts salts and their classification acids, bases and salts chemistry

Ashish mixed a solution of soluble silver nitrate and soluble sodium chloride. The products formed are :

  1. soluble silver chloride and soluble sodium nitrate

  2. insoluble silver chloride and insoluble sodium nitrate

  3. insoluble silver chloride and soluble sodium nitrate

  4. soluble silver chloride and insoluble sodium nitrate
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To make an insoluble salt, it is possible to make two soluble salts react together in a precipitation reaction. Silver nitrate and sodium chloride are both soluble. When mixing their solutions together, the result is insoluble silver chloride and soluble sodium nitrate.

Multiple choice salts salts and their classification acids, bases and salts chemistry

What is the state of a precipitated compound?

  1. $(l)$
  2. $(g)$
  3. $(aq)$
  4. $(s)$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Precipitation is the formation of solid from a solution. When the reaction occurs in a liquid solution, the solid formed is called the 'precipitate'. The chemical that causes the solid to form is called the 'precipitant'.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Which of the following will be formed, if we heat an aqueous solution of $AlCl _3$ to dryness?

  1. Solid $AlCl _3$
  2. Dimer $Al _2Cl _6$
  3. $Al(OH) _3$
  4. $Al _2O _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

We knoe $AlCl _3$ exists as a dimer $Al _2Cl _6$

The reactions involved are given by,
$Al _2Cl _6 .6H _2O \rightarrow Al _2O _3+3H _2O+6HCl$
So,option D is correct answer.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

An inorganic compound $A$ shows the following reaction:
(i) It is white solid, exists as dimer and fumes in the wet air.
(ii)It sublimes at $180^{ \circ  }C$ and forms monomer if heated to $400^{ \circ  }C$.
(iii) Its aqueous solution turns blue litmus to red and gives a white precipitate with $AgNO _3$ solution, which is soluble in $NH _4OH$.
Addition of $NH _4OH$ and NaOH separately to the solution of $A$ gives a gelatinous precipitate which in however soluble in excess of $NaOH$.
The compound $A$ is:

  1. $Al(OH) _3$
  2. $Al _2Cl _6$
  3. $Al _2O _3$
  4. $Al _2(SO _4) _3$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

(B) Compound $B$ is ${Al} _{2}{Cl} _{6}$.

(i) ${Al} _{2}{Cl} _{6}$ is a white solid, exists as dimer and fumes in wet air.
(ii) It sublimes at 180°C and converts into $Al{Cl} _{3}$ at 400°C.
(iii) Its aqueous solution is acidic, so it turns blue litmus to red.
${Al} _{2}{Cl} _{6} + 6{H} _{2}O \; \longrightarrow \; \underset{\text{(weak base)}}{2Al{(OH)} _{3}} + \underset{\text{(strong acid)}}{6HCl}$.
It gives white ppt. with $AgN{O} _{3}$ which is soluble in $N{H} _{4}OH$.
(iv)$Al{Cl} _{3} + 3NaOH \; \longrightarrow \; \underset{\text{(white ppt.)}}{2Al{(OH)} _{3}} + 3NaCl$
$Al{(OH)} _{3} + \underset{\text{(excess)}}{NaOH} \; \longrightarrow \; \underset{\text{(soluble)}}{NaAl{O} _{2}} + 2{H} _{2}O$
But in case of $N{H} _{4}OH$, the ppt. of $Al{(OH)} _{3}$ does not dissolve in excess of $N{H} _{4}OH$.