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 substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

On long standing, bleaching powder undergoes auto-oxidation into:

  1. $Ca(ClO _3) _2, CaCl _2$
  2. $CaO, CaCl _2$
  3. $CaClO, CaClO _3$
  4. $CaClO _2, CaCl _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

On long standing, bleaching powder undergoes auto-oxidation into calcium chlorate $Ca(ClO _3) _2$ and $ CaCl _2$.
 $6CaOCl _2 \rightarrow 6 Ca(ClO _3) _2  + 5 CaCl _2$.
The bleaching powder is $CaOCl _2$

Multiple choice chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

On long standing, bleaching powder undergoes auto oxidation.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

On long standing, bleaching powder undergoes auto-oxidation which results in the formation of calcium chloride and calcium chlorate.


$6 CaOCl _2 \rightarrow5CaCl _2   + 6 Ca(ClO3) _2 $

Hence, the given statement is $true$

Multiple choice chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

Substance $X$:
(I) reacts with $H _2S$ to produce white turbidity.
(II) changes light green solution of $FeSO _4$ into yellow colour.
(III) reacts with moisture to give pungent smelling gas.
Hence $X$ is:

  1. $KMnO _4$
  2. $K _2Cr _2O _7$
  3. $SO _2$
  4. $CaOCl _2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$CaOCl _2+H _2O\rightarrow Ca(OH) _2+\underset {(\text {Pungent smelling gas})}{Cl _2}\uparrow$
$H _2S+Cl _2\rightarrow 2HCl+\underset {(\text {White turbidity})}{S}$
$\underset {(\text {Light green})}{2FeSO _4}+H _2SO _4+Cl _2\rightarrow Fe _2(SO _4) _3+2HCl$

Multiple choice chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

The bleaching property of chlorine water is due to:

  1. formation of nascent oxygen

  2. formation of nascent chlorine
  3. formation of ${O} _{3}$
  4. reducing property of ${Cl} _{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
${ Cl } _{ 2 }+{ H } _{ 2 }O\rightarrow HCl+HOCl\rightarrow 2HCl+\left[ 0 \right] $
$\left[ 0 \right] $-Nascent oxygen
Chlorine water act as strong oxidizing agent because of nascent oxygen produced in water.
Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

Which of the following pairs is obtained on heating ammonium dichromate?

  1. $\displaystyle { N } _{ 2 }$ and $\displaystyle { H } _{ 2 }O$
  2. $\displaystyle { N } _{ 2 }O$ and $\displaystyle { H } _{ 2 }O$
  3. $\displaystyle { NO } _{ 2 }$ and $\displaystyle { H } _{ 2 }O$
  4. $\displaystyle NO$ and $\displaystyle { NO } _{ 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ammonium dichromate on heating gives nitrogen, chromic oxide and water.
$\displaystyle { \left( { NH } _{ 4 } \right)  } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }\underrightarrow { \Delta  } { N } _{ 2 }+{ Cr } _{ 2 }{ O } _{ 3 }+4{ H } _{ 2 }O$

Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

An element X combines with hydrogen to form a compound $XH _3$. The element X is placed on the right side ofthe periodic table. What is true about the element X?
A. Has 3 valence electrons.
B. Is a metal and is solid.
C. Is a non-metal and is a gas.
D. Has 5 valence electrons.
E. $XH _3$  reacts with water to form a basic compound?

  1. A, B and C

  2. B,C and D

  3. C, D and E

  4. E, A and B
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Here, $X$ is nitrogen with atomic number 7 and electronic configuration $ { 1s }^{ 2 }{ 2s }^{ 2 }{ 2p }^{ 3 } $ 

It is a non metal belonging to group 15.
Solution of ammonia In water is alkaline in nature and is highly soluble in water.

Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

Select the correct statement for brown ring test.

  1. Nitrates are converted to $NO$
  2. $NO$ forms complex with $Fe$
  3. $Fe^{2+}$ acts as reducing agent here.

  4. Brown colour is due to the complex formation.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation
$ 2HNO _3+ 3H _2SO _4 + 6FeSO _4 \rightarrow 3Fe _2(SO _4) _3 + 2NO + 4H _2O $ $[Fe(H _2O) _6]SO _4+NO \rightarrow [Fe(H _2O) _5(NO)]SO _4+H _2O$ Nitrates are converted into nitric oxide. $NO$ forms complex with $Fe$. $Fe^{2+}$ acts as reducing agent. $[Fe(H _2O) _5(NO)]SO _4$ is brown coloured complex formed.
Multiple choice chemistry p- block elements-ii anomalous properties of nitrogen nitrogen - 15 group group 15 elements

Alkali metals dissolve in liquid ammonia and produces _______.

  1. deep blue solution

  2. a solution which are conducting in nature

  3. red coloured solution
  4. Both $1$ and $2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alkali metal when reacts with liquid ammonia reaction is given by,


$ M +(x+y) NH _3\rightarrow M^+(NH _3)x + e^{-}(NH _3) _y$

 this electrons is free and gives very good conductivity as well blue colour.

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

Alkali metals readily react with oxyacids forming corresponding salts like ${ M } _{ 2 }{ CO } _{ 3 }$, ${ M }H{ CO } _{ 3 }$, ${ M }N{ O } _{ 3 }$, ${ M } _{ 2 }{ SO } _{ 4 }$, etc. with evolution of hydrogen. They also dissolve in liquid ${ NH } _{ 3 }$ but without the evolution of hydrogen. The color of its dilute solution is blue but when it is heated and concentrated then its color becomes bronze.

Which of the following statement about the sulphate of alkali metal is correct :

  1. except ${ Li } _{ 2 }{ SO } _{ 4 }$ all sulphate of other alkali metals are soluble in water.

  2. all sulphates of alkali metals except lithium sulphate forms alum.

  3. the sulphates of alkali metals cannot be hydrolysed.

  4. all of these.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Except ${ Li } _{ 2 }{ SO } _{ 4 }$ all sulphate of other alkali metals are soluble in water and forms alum. Thus, they form double salts with the sulphates of trivalent metals like $Al, Fe, Cr$ etc. The sulphates of alkali metals cannot be hydrolysed as they are salts of a strong acid and strong base. 
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

$LiOH$ reacts with $CO {2}$ to form $Li _{2}CO _{3}$ (atomic mass of $Li = 7)$. The amount of $CO _{2}$ (in g) consumed by $1\ g$ of $LiOH$ is closest to ______.

  1. $0.916$
  2. $1.832$
  3. $0.544$
  4. $1.088$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Balanced chemical equation is:

$2LiOH+C{ O } _{ 2 }\rightarrow { Li } _{ 2 }C{ O } _{ 3 }+{ H } _{ 2 }O$
Molecular weight of each specie is:
$LiOH$=24 g/mol; $C{ O } _{ 2 }$=44 g/mol; ${ Li } _{ 2 }C{ O } _{ 3 }$= 74 g/mol; ${ H } _{ 2 }O$=18 g/mol
From the reaction:
2 mol of $LiOH$ ($24\times2=48\ g$) consumes 1 mol of $CO _2$ (44 g)
Therefore, 1 g of $LiOH$ will consume $\frac { 1 }{ 48 } \times 44\quad g\quad C{ O } _{ 2 }=0.916\ g\ CO _2$
Option A is the correct answer.

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

_________ cannot be readily separated by physical means.

  1. Mixtures

  2. Metals

  3. Alloys

  4. Non-metals
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Alloys are metallic materials consisting of two or more elements combined in such a way that they cannot be readily separated by physical means. More than 90% of metals used are in the form of alloys.