Tag: chemistry

Questions Related to chemistry

Which of the following is not a characteristic of alcohol ?

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. They are lighter than water.

  2. Their boiling points rise fairly uniformly with rising molecular weight.

  3. Lower members are insoluble in water and organic solvents but the solubility regularly increases with molecular mass.

  4. Lower members have a pleasant smell and burning taste, higher members are colourless and tasteless.

  5. Higher members have a pleasant smell and burning taste, lower members are colourless and tasteless.

Show answer
Correct Option: C
Explanation:
A. Alcohols are lighter than water because water molecules are closely packed together due to extensive H-bonding, which means that it has more mass in the same volume than either alcohol or oil. In addition, alcohol is made up of carbon and hydrogen atoms while water is made up of oxygen and hydrogen atoms.
B. Their boiling points rise fairly uniformly with rising molecular weight this is because boiling point depends on the intermolecular interactions such as H-bonding which decreases as the chain length decreases.
C. Lower members are soluble in water and organic solvents but the solubility regularly decreases with molecular mass because of ease of H-bonding in smaller alcohol molecules than those having long hydrocarbon chain.
D. Lower members have a pleasant smell and burning taste, higher members are colourless and tasteless.

Unlike phenol, 2,4-dinitrophenol is soluble in sodium carbonate solution in water because ?

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. presence of two - $NO _2$ groups in the ring makes 2 , 4 - dinitrophenol a stronger acid than phenol.

  2. presence of two - $NO _2$ groups in the ring makes 2 , 4 - dinitrophenol a weaker acid than phenol.

  3. presence of two $-NO _2$ groups make the hydrogen bonding easier, making 2 , 4-dinitrophenol soluble.

  4. nitro group reacts with $Na _2CO _3$ while -$OH$ group does not.

Show answer
Correct Option: A
Explanation:

Presence of two electron withdrawing $-No _2$ groups in the ring makes 2,4-dinitrophenol a stronger acid than phenol. Hence it react with aqueous  $Na _2CO _3$ solution to form sodium salt thus making it soluble in $Na _2CO _3$ . 

The compound which gets dissolved in water is :

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. $C _{2}H _{6}$

  2. $C _{2}H _{4}$

  3. $C _{2}H _{2}$

  4. $C _{2}H _{5}OH$

  5. $C _{3}H _{8}$

Show answer
Correct Option: D
Explanation:

Option D or Ethanol dissolves in water. 


Ethanol has electronegative oxygen atom in it, and hence it takes part in hydrogen bonding with water. 

Because of excessive hydrogen bonding with water, Ethanol dissolves in it.

Which of the following cannot be dissolved in alcohol?

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. Dyes and drugs

  2. Soaps and varnishes

  3. Resins and varnishes

  4. Rubber and plastics

Show answer
Correct Option: D
Explanation:

Rubber and plastic cannot be dissloved in alchol because of nonpolar nature of rubber and plastics

Which of the following has a higher boiling point?

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. Butanol

  2. Butanal

  3. Both of them have similar boiling point

  4. Cannot say anything 

Show answer
Correct Option: A
Explanation:

There is a large difference between boiling points of butanol and butanal, although they have almost the same solubility in water. Butanol contains -OH group and can form hydrogen bonds. Hence, the molecules are associated. A large amount of energy is required to break the association. Hence, butanol has a higher boiling point. Hydrogen bonding is not possible in butanal.

Solubility of alcohols in water is _______ to that of hydrocarbons of comparable molecular masses.

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. greater than

  2. similar

  3. lesser than

  4. none of these

Show answer
Correct Option: A
Explanation:
Since alcohols can participate in $H-$bonding while hydrocarbons cannot, alcohols are able to interact with water molecules more easily than hydrocarbons of comparable molecular masses. Hence alcohols possess greater solubility in water than hydrocarbons of comparable molecular masses.
Lower alcohols are more soluble in water than higher alcohols.
chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Lower alcohols are more soluble in water than higher alcohols. With the increase in the molar mass, solubility decreases. In alcohols, $-OH$ group is polar and forms hydrogen bonds with water. This makes alcohol water soluble. The alkyl chain (hydrocarbon chain) is non-polar and decreases the solubility of alcohol in water.

Alcohols containing only up to ________________ carbon atoms are completely miscible with water.

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. 10

  2. 3

  3. 8

  4. 14

Show answer
Correct Option: B
Explanation:

 Alcohol-containing up to $3-$ carbon atoms are completely miscible with water in all proportions. This is due to the hydrogen bonding with water molecule. 

Melting point of phenol is :

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. $53^0C$

  2. $43^0C$

  3. $33^0C$

  4. $23^0C$

Show answer
Correct Option: B
Explanation:

Pure phenols are generally colorless solids or liquids. Phenols (molecular weight $=94$) have the relatively low melting point. So generally exist in liquid form above room temperature.

its melting point is $43^0C$.

Which of the following is not true regarding phenol?

chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

  1. Pure phenol is a white crystalline solid

  2. Phenol smell as disinfectant.

  3. It causes immediate white blistering to the skin

  4. None of these

Show answer
Correct Option: D
Explanation:

Pure Phenols are colorless solids or liquids. These are used as disinfectant due to their chemical properties. Also, because of its acidic nature, it causes immediate white blistering to the skin.