Chemistry

Organic Chemistry Fundamentals

237 Questions

Organic chemistry fundamentals cover the structure, properties, and reactions of carbon containing compounds. The questions explore functional groups, isomerism, homologous series, and basic reaction mechanisms. This forms the basis of general chemistry across multiple examination formats.

Functional groupsIsomerism typesHomologous seriesCycloalkanesOrganic monomers

Organic Chemistry Fundamentals Questions

Multiple choice law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

Which one of the following sets of compounds correctly illustrate the law of reciprocal proportions.

  1. $P _{2}O _{3}, PH _{3}, H _{2}O$
  2. $P _{2}O _{5}, PH _{3}, H _{2}O$
  3. $N _{2}O _{5}, NH _{3}, H _{2}O$
  4. $N _{2}O, NH _{3}, H _{2}O$
  5. $NO _{2}, NH _{3}, H _{2}O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Law of Reciprocal proportions:-

When two different elements combine with the same mass of a $3^{rd}$ element, the ratio of masses in which they do so must be same or multiple of the mass ratio in which they combine with each other.
$A)$ $P _2O _3,PH,H _2O$
The ratio of phosphorous combining with oxygen in $P _2O _3$ is 
$P:O=62:48=31:24$
The ratio of Phosphorous combining with hydrogen in $PH _3$ is
$P:H=31:3$
The ratio of hydrogen combining with oxygen in $H _2O$ is 
$H:O=2:16=1:8$       $\longrightarrow 1$
Now, the ratio of hydrogen & oxygen combining with $P$
$\Rightarrow 3:24=1:8$     $\longrightarrow 2$
From $1$ & $2$,  $1:8$ is same in both cases
$\therefore$ Law of reciprocal proportions is illustrated correctly.

Multiple choice law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

Which of the following sets of compounds correctly illustrate the law of reciprocal proportion ?

  1. $N _2O,NH _3,SO _2$
  2. $P _2O _5,PH _3,H _2O$
  3. $NO _2,NH _3,SO _3$

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

The law of reciprocal proportions is one of the basic laws of stoichiometry. It relates the proportions in which elements combine across a number of different elements. A simple statement of the law is:

 Element A combines with element B and also with C, then, if B and C combine together, the proportion by weight in which they do so will be simply related to the weights of B and C which separately combine with a constant weight of A.

Hydrogen combines with Oxygen to form ${ H } _{ 2 }O$

$2:16\\ 1:8$

Phosphorous combines with Oxygen to form ${ P } _{ 2 }O _{ 5 }$

$62:80\\ 31:40\\ $

Phosphorous combines with Hydrogen to form $P{ H } _{ 5 }$

$31:5\\ \cfrac { 31 }{ 40 } \times \cfrac { 8 }{ 1 } =\cfrac { 31 }{ 5 } $

Multiple choice chemistry the language of chemistry percent composition percentage composition and empirical formula empirical formula, percentage composition and molecular formula

Which of the following compound represents an alkane?

  1. ${C} _{5}{H} _{8}$
  2. ${C} _{7}{H} _{16}$
  3. ${C} _{8}{H} _{6}$
  4. ${C} _{9}{H} _{10}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Alkanes have general molecular formula is $C _nH _{2n+2}$


$\therefore C _7H _{16}$ is Alkane.

Hence, the correct option is $\text{B}$

Multiple choice isomerism of amines organic compounds with functional group containing nitrogen

The number of isomeric primary amine possible for the formula $C _3H _9N$ :

  1. 2

  2. 3

  3. 5

  4. 6
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The following primary amines are possible for $C _3H _9N$

(i) $CH _3-CH _2-CH _2-NH _2$    propyl amine
(ii) $CH _3-\underset {|}{CH}-CH _3$                   $2-$aminopropane   (Isopropyl amine)
                  $NH _2$
$\therefore 2$ primary amines are possible.

Multiple choice isomerism of amines organic compounds with functional group containing nitrogen

A racemic mixture contains equal _____ of dextrorotatory and laevorotatory isomers.

  1. No. of molecules

  2. Masses

  3. No. of moles

  4. All the above are correct.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A racemic mixture contains equal no. of moles or no. of molecules or masses because the only rotation is different, one is having d and another is having l.

Multiple choice isomerism of amines organic compounds with functional group containing nitrogen

How may total structural isomers of $3^o$ amines are possible with the molecular formula $C _6H _{15}N$

  1. 4

  2. 7

  3. 6

  4. 5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For a tertiary (3 degree) amine with formula C6H15N, the nitrogen is bonded to three alkyl groups. The possible combinations of alkyl groups (summing to 6 carbons) are: (methyl, methyl, butyl) - 2 isomers; (methyl, ethyl, propyl) - 2 isomers; (ethyl, ethyl, ethyl) - 1 isomer; (methyl, isopropyl, ethyl) - 1 isomer; (methyl, propyl, ethyl) - 1 isomer. Total is 7.

Multiple choice isomerism of amines organic compounds with functional group containing nitrogen

In the given example B,C and B,D are :

(a) $CH _3-CH _2-CH _2 - CH _2NH _2$
Butanamine $(1^o)$

(b) $CH _3-CH _2-\overset{NH _2}{\overset{|}{C}H} - CH _3$ 
Butan-2-amine $(1^o)$

(c) $CH _3-\overset{CH _3}{\overset{|}{C}H} - CH _2-NH _2$
2-Methylpropanamine $(1^o)$

(d) $CH _3-\!\!\!\!\underset{\quad CH _3}{\underset{|}{\overset{\quad CH _3}{\overset{|}{C}}}\!\!\!\!-}NH _2$
2-methylpropan-2-amine $(1^o)$

(e) $CH _3-CH _2-CH _2-NH - CH _3$
N-methylpropanamine $(2^o)$

  1. Positional isomers

  2. Chain isomers

  3. Functional isomers

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

B,C and B,D are exbhits chain isomerism as the pairs are differed in their longest chain. Hence option B is correct.

Multiple choice isomerism of amines organic compounds with functional group containing nitrogen

Which of the following type/(s) of isomerism is shown in  the amine of the formula $C _4H _{11}N$ :

  1. Chain isomerism

  2. Metamerism

  3. Position isomerism

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The amine of the formula $C _4H _{11}N$ shows chain  isomerism, metamerism, position  isomerism as well as functional group  isomerism.

Multiple choice isomerism of amines organic compounds with functional group containing nitrogen

In the given compound A,C and A,D are exbhits which of the following isomerism :

(a) $CH _3-CH _2-CH _2 - CH _2NH _2$
Butanamine $(1^o)$

(b) $CH _3-CH _2-\overset{NH _2}{\overset{|}{C}H} - CH _3$ 
Butan-2-amine $(1^o)$

(c) $CH _3-\overset{CH _3}{\overset{|}{C}H} - CH _2-NH _2$
2-Methylpropanamine $(1^o)$

(d) $CH _3-!!!!\underset{\quad CH _3}{\underset{|}{\overset{\quad CH _3}{\overset{|}{C}}}!!!!-}NH _2$
2-methylpropan-2-amine $(1^o)$

(e) $CH _3-CH _2-CH _2-NH - CH _3$
N-methylpropanamine $(2^o)$

  1. Chain isomerism

  2. position isomerism

  3. Functional isomerism

  4. Metamerism
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A,C and A,D are exbhits chain isomerism as the pairs are differed in their longest chain. Hence option A is correct.

Multiple choice chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

In which compound enol form is maximum

  1. $CH _3-\overset{\overset{O}{||}}C-CH _3$
  2. ${ CH } _{ 3 }-CH=O$
  3. ${ CH } _{ 3 }-\underset { || }{ C } -{ CH } _{ 2 }-CH _3\\ \quad \quad \quad O$
  4. ${ CH } _{ 3 }-{ CH _2 } -{ CH } _{ 3 }\\ \quad \quad \quad \quad $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Enol content is higher in beta-dicarbonyl compounds due to intramolecular hydrogen bonding and resonance stabilization of the enol form. Option C is a beta-diketone.