Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

Multiple choice methane study of methane carbon- an important element hydrocarbons chemistry

Statement I: Methane is defined as a compound
Statement II: Methane can be broken down chemically

  1. Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1

  2. Both the Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1

  3. Statement 1 is correct but Statement 2 is not correct.

  4. Statement 1 is not correct but Statement 2 is correct.

  5. Both the Statement 1 and Statement 2 are not correct.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Statement I: methane is defined as a compound
statement II: Methane can be broken down chemically
Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.
Note: Compounds are defined as substances of definite compositions which can be decomposed into two or more substances by a simple chemical process.

Multiple choice methane study of methane carbon- an important element hydrocarbons chemistry

The correct composition of water gas is :

  1. mixture of $H _2$ and $CO$
  2. mixture of $N _2$ and $CO$
  3. mixture of $He$ and $CO$
  4. mixture of $O _2$ and $CO$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water gas is produced from synthesis gas, which is composed of carbon monoxide and hydrogen. Syngas is a useful product, but requires careful handling due to its flammability and the risk of carbon monoxide poisoning. 

Multiple choice methane study of methane carbon- an important element hydrocarbons chemistry

Reaction of methane with halogens under appropriate conditions is called as :

  1. Halogenation

  2. Free radical halogenation

  3. Methylation

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

Methane reacts with halogens given appropriate conditions as follows:

${X} _{2} + UV \rightarrow  2 X \cdot$

$X \cdot + C{H} _{4} \rightarrow HX + C{H} _{3} \cdot$

$C{H} _{3} \cdot + {X} _{2} \rightarrow C{H} _{3}X + X \cdot$

where $X$ is a halogen: fluorine $\left(F\right)$, chlorine $\left(Cl\right)$, bromine $\left(Br\right)$, or iodine $\left(I\right)$. This mechanism for this process is called free radical halogenation.

Multiple choice acyl chlorides carboxylic acids and their derivatives functional derivatives of carboxylic acids carbonyl compounds chemistry

Which of the following cannot be named as a derivative of $CH _{3}COOH$?

  1. $CH _{3}CH _{2}COOH$
  2. $(CH _{3}) _{2}CHCOOH$
  3. $HCOOH$
  4. $(CH _{3}) _{3}CCOOH$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Option A, B and D can be derived from $CH _3 COOH$ while option C, i.e., $HCOOH$ cannot be derived from $CH _3COOH$ as $HCOOH$ has one carbon less than $CH _3COOH$.


Option C is correct.

Multiple choice acyl chlorides carboxylic acids and their derivatives functional derivatives of carboxylic acids carbonyl compounds chemistry

Which of the following statements is wrong?

  1. For the synthesis of esters from carboxylic acids and alcohols, we can often use a base as a catalyst.

  2. For the synthesis of esters from carboxylic acids and alcohols, we can often use an additional acid as a catalyst.

  3. For the alkaline hydrolysis of carboxylic esters, we need to use an excess of base.

  4. For the hydrolysis of carboxylic esters under acidic conditions, we need only a catalytic amount of an additional acid.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Esterification (Fischer esterification) is acid-catalyzed. Using a base would result in a saponification-like reaction or simply fail to catalyze the formation of the ester from the acid and alcohol.

Multiple choice acyl chlorides carboxylic acids and their derivatives functional derivatives of carboxylic acids carbonyl compounds chemistry

With which of the following can ethyl ethanoate not undergo a substitution reaction?

  1. $CH _3CO _2Na$
  2. aqueous $NaOH$
  3. $CH _3OH$, $H^+$
  4. aqueous $NH _3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ethyl ethanoate is an ester. Sodium acetate (CH3CO2Na) is the salt of the carboxylic acid component of the ester and does not act as a nucleophile to substitute the ethoxy group in a standard substitution reaction.

Multiple choice acyl chlorides carboxylic acids and their derivatives functional derivatives of carboxylic acids carbonyl compounds chemistry

Amides and acid chlorides are:

  1. organic functional group

  2. functional derivative of carboxylic acid
  3. both $A$ and $B$

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

Amides and Acid chlorides are organic Functional group and functional derivative of carboxylic acid. Amide has general formula $\displaystyle  R - \underset {   \underset {\displaystyle O}{||}  }{C} - NH _2  $. Carboxylic acid has general formula $\displaystyle  R - \underset {   \underset {\displaystyle O}{||}  }{C} - OH  $. An example of amide is acetamide $\displaystyle  CH _3 - \underset {   \underset {\displaystyle O}{||}  }{C} - NH _2   $. An example of carboxylic acid is acetic acid $\displaystyle  CH _3 - \underset {   \underset {\displaystyle O}{||}  }{C} - OH  $. Acid chloride has general formula $\displaystyle  R - \underset {   \underset {\displaystyle O}{||}  }{C} - Cl  $.  An example of acid chloride is acetyl chloride $\displaystyle  CH _3 - \underset {   \underset {\displaystyle O}{||}  }{C} - Cl  $. 

Multiple choice acyl chlorides carboxylic acids and their derivatives functional derivatives of carboxylic acids carbonyl compounds chemistry

As the molecular weight increases the boiling point of carboxylic acid:

  1. increases

  2. decreases

  3. remain same

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

As the molecular weight increases the boiling point of carboxylic acid increases. Lower aliphatic carboxylic acids (upto 9 C atoms) are liquids, the higher members are wax like solids.