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 adsorption and colloids applications of colloids colloids around us the colloidal state

Argyrol is a:

  1. Ferric oxide sol

  2. Silver sol

  3. Gold sol

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

Argyrol is a silver sol and is used as an eye lotion.It is manufactured in the chemical industry to pharmaceutical grade only, using denatured pharmaceutical-grade protein for ophthalmic application and elemental silver, to produce the silver protein molecule.

Multiple choice chemistry adsorption and colloids applications of colloids colloids around us the colloidal state

To stop bleeding from an injury ferric chloride can be applied
Which comment about the statement is justified?

  1. It is not true, ferric chloride is a poison
  2. It is true, ${Fe}^{3+}$ ions coagulate blood which is negatively charged sol
  3. It is not true, ${Cl}^{-}$ ions from positively charged sol, profuse bleeding takes place
  4. It is true, coagulation takes place because of formation of negatively charged sol with ${Cl}^{-}$ ions.

  5. It is not true, ferric chloride is ionic and gets into blood stream
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To stop bleeding from an injury, Ferric chloride can be applied because of the following reason:

(A) $Fe^{3+}$ ions coagulate blood which is a negatively charged solution
(B) $Cl^−$ ions coagulate blood which is a positively charged solution

Blood being a colloidal solution, its coagulation by Hardy-Shuze's law states " Higher the charge on cation higher will be its efficiency to coagulate the colloidal solution" . Thus Option B is correct.

Multiple choice chemistry further aspects of equilibria indicators and acid-base titration study of indicators properties of acids and bases

A solution containing $Fe^{2+}$ ions is titrated with $KMnO _{4}$ solution. Indicator used will be:

  1. phenolphthalein

  2. methyl orange

  3. litmus

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

Titration of ${ Fe }^{ 2+ }$ with ${ KMnO } _{ 4 }$ is an redox titration.

${ Fe }^{ 2+ }+\underbrace { 7{ MnO } _{ 4 }^{ - } } +14{ H }^{ + }={ Fe }^{ 3+ }+\underbrace { 7{ Mn }^{ 2+ } } +7{ H } _{ 2 }O$
                  violet                                     colourless
So, phenolpthalein, methyl orange and litmus are all acid base indicators. They can't be used in this redox titration. ${ KMnO } _{ 4 }$ is a self-indicator changing from violet to colourless.
$\therefore$   Answer will be $D$.

Multiple choice chemistry further aspects of equilibria indicators and acid-base titration study of indicators properties of acids and bases

$0.1\ N$ solution of $Na _{2}CO _{3}$ is being titrated with $0.1\ N\ HCl$, the best indicator to be used is:

  1. potassium ferricyanide

  2. phenolphthalein

  3. methyl orange

  4. litmus
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Titration of ${ Na } _{ 2 }{ CO } _{ 3 }$ with $HCl$ involves following two reaction :
a) ${ Na } _{ 2 }{ CO } _{ 3 }+HCl\rightleftharpoons { NaHCO } _{ 3 }+NaCl$
b) ${ NaHCO } _{ 3 }+HCl\rightleftharpoons NaCl+{ H } _{ 2 }O+{ CO } _{ 2 }\quad \left\{ { H } _{ 2 }{ CO } _{ 3 }-carbonic\quad acid \right\} $
We know phenolphthalein is an indicator and it works in the basic medium that is why it causes only $50$% of neutalisation of ${ Na } _{ 2 }{ CO } _{ 3 }$ because in the step $b$ the medium turns acidic due to formation of ${ H } _{ 2 }{ CO } _{ 3 }$ and phenolphatein will not work. On the other hand methyl orange is a basic indicator and works in the acidic medium and causes $100$% neutralisation of ${ Na } _{ 2 }{ CO } _{ 3 }$.
Answer will be $C$.
Multiple choice chemistry study of compounds a. hydrogen chloride laboratory method of preparation of hydrochloric acid physical and chemical properties and uses of hydrochloric acid hydrogen chloride: occurrence, preparation, purification and identification

Compounds $A$ and $B$ are treated with dilute $HCl$ separately. The gases liberated are $Y$ and $Z$ respectively $Y$ turns acidified dichromate paper green while $Z$ turns lead acetate paper black. So $A$ and $B$ compounds are respectively:

  1. $Na _2SO _3, Na _2S$
  2. $NaCl, Na _2CO _3$
  3. $Na _2S, Na _2SO _3$
  4. $Na _2SO _3, K _2SO _4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Na2SO3 + HCl produces SO2 gas, which turns acidified dichromate paper green. Na2S + HCl produces H2S gas, which turns lead acetate paper black. Thus, A is Na2SO3 and B is Na2S.

Multiple choice chemistry study of compounds a. hydrogen chloride laboratory method of preparation of hydrochloric acid physical and chemical properties and uses of hydrochloric acid hydrogen chloride: occurrence, preparation, purification and identification

Which compound(s) is/are produced when hydrochloric acid is added to silver nitrate solution?

  1. ${ HNO } _{ 3 }$
  2. $AgCl$

  3. Both A and B

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

${ AgNO } _{ 3 }+HCl\rightarrow AgCl+{ HNO } _{ 3 }$

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Which of the following salt gives a crimson red colour in flame test?

  1. $BaCl _{2}$
  2. $CaCl _{2}$
  3. $BeCl _{2}$
  4. $SrCl _{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Strontium chloride($SrCl _2$) gives crimson red colour in the flame test. It is due to the excitation of electrons by the thermal energy, which is then followed by de-excitation of electron to ground state along with liberation of light in the visible range.

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Which of the following does/do not impact characteristic colour to the flame?

  1. $MgSO _4$
  2. $CaCl _2$
  3. $Sr(NO _3) _2$
  4. $BeCl _2$
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

$CaCl _2$ has orange colour.
$Sr(NO _3) _2$ has crimson colour flame.


Be and Mg do not impart any colour to the flame due to higher ionization energy and small size.The energy of the flame is not sufficient to excite the electrons to higher energy levels. Hence, they do not impart any characteristic colour to the flame