Pyqs in Chemistry

10 pyqs with solutions for scientific assistant for chemistry 

1. Which of the following is an example of a lewis acid?

1. HCL

2. H2SO4

3. AlCl3

4. NaOH

Answer: AlCl3 

Explanation: Since lewis acid is a electron acceptor comparing to all other options AlCl3 only accepts electrons.

2.   Which of the following is most acidic?

1. O- nitrophenol

2. Phenol

3. O- cresol 

4. m-cresol

Answer: O-nitrophenol

Explanation: Since the nitro group is EWG, the proton in the OH group can easily leaves making it acidic

3.   Which of the following properties increases from left 

       to right across a period in the periodic table?

1. Atomic radii

2. Ionization enthalpy 

3. Atomic mass

4. Metallic conductivity 

 

Answer: Ionization enthalpy 

Explanation: Since moving from left to right across    period the electrons can be pulled more towards the nucleus leading to increased energy for its removal.

 4.  Which of the following is not a characteristic of an acid?

1. It turns blue litmus paper red

2. It has a sour taste

3. It reacts with bases to form salt and water

4. It turns red litmus paper blue

Answer: It turns red litmus Paper blue

Explanation: The property of acids is to turn blue litmus  paper red.

5.   Slaters rule are used to calculate?

1. Atomic mass

2. Atomic radius 

3. Ionization energy

4. Effective nuclear charge 

Answer: Effective nuclear charge

Explanation: Used to calculate effective nuclear charge experienced by an electron in a multi-electron atom.

6.  Nylon 6,6 is prepared from

1. Hexamethylene diamine and adipic acid

2. Caprolactone

3. Caprolactam

4. Hexamethylene diamine and oleic acid

Answer: Hexamethylene diamine and aceticacid

Explanation: Nylon 6,6 is a Synthetic polyamide formed the condensation of Hexamethylene diamine and Adipic acid

7.   Which of the following favours SN2 reaction 

1. Tertiary substrate

2. Bulky nucleophile

3. Polar aprotic solvent

4. High temperature 

Answer: polar aprotic solvent

Explanation: Polar aprotic Solvents like acetone DMSO DMF don't easily solvate nucleophile keeping it reactive

8.   What happens in homolytic Fission?

1. Two electrons are shared between two atoms

2. One electron is transferred from one atom to other

3. Two electrons are split between two atoms, each atom receiving one electron

4. One atom takes both electrons from a covalent bond

 Answer: Option C

 Explanation: In homolytic fission of an atom the gets splitted equally each atom receiving one electron 

9.   Bakelite is

1. Phenol- formaldehyde polymer

2. Polyurethane

3. Polyaramide

4. Polyetherimide

Answer: Option a

Explanation: Bakelite is the

            world’s first synthetic plastic

            made from condensation of

            Phenol and formaldehyde

10.   Which class of organic compounds are commonly

         used as fragrances and flavourings?

1. Aldehydes

2. Ketones 

3. Alcohols

4. Esters

Answer: Esters

Explanation: Esters are 

            known for their pleasant fruity

            odours and is used as

            Fragrances and flavourings