P-Block-Quiz-8

P-Block Quiz-8

Dear Readers,

The one subject in NEET which is candidates who can easily attain good marks is Chemistry. That's the reason, often, one doesn’t pay notice and choose to compromise it. But if one wants to rank above others, the tip is to be thorough with NEET chemistry concepts. The understanding of reactions and definite basic understanding is what requires major attention in Chemistry but once done it only gets simpler from there. The main focus on the to-do list should be on getting a hang of the NCERT syllabus of NEET chemistry..

Q1. Red lead is:

•  PbO
•  
•  
•  HgS

Solution
It is also known as minium or sindhur.

Q2.Boron halides behave as Lewis acids because of their ……… nature.

•  Proton donor
•  Covalent
•  Electron deficient
•  Ionising

Solution
According to Lewis, the compound which can accept a lone pair of electron, are called acids. Boron halides, being electron deficient compounds, can accept a lone pair of electrons, so termed as Lewis acid.

Q3.  Purification of alumina takes place by

•  Bosch process
•  Hall’s process
•  Hoope’s process
•  Quartation process

Solution
Hall’s process is used for purification of alumina. Hoope’s process is used for refining of alumina.

Q4. Buckminster-fullerene is a variety of

•  Boron
•  Carbon
•  Ammonia
•  Fluorine

Solution
A recently discovered family of carbon allotropes is buckminster fullerene. The most common fullerene has the formula  and contains hexagonal and pentagonal rings of carbon atoms. Hence, in ketones the two valencies of carbonyl group are satisfied by alkyl groups.

Q5.Which one of the following compounds, is not a protonic acid?

•  
•  
•  
•  

Solution
  is not protonic acid because it does not give proton on ionisation directly while it acts as Lewis acid due to a acceptance of from water and forms a hydrated species.

Q6. Glass is a

•  Micro crystalline solid
•  Gel
• Super cooled liquid
•  Polymeric mixture

Solution
Super cooled liquid

Q7.There are two H-bridge bonds in diborane molecule because there are:

•  Only 12 electrons
•  14 electrons
•  2 electrons less than required for bonding
•  Two electrons more than required for bonding

Solution
Diborane possesses four B—H covalent bonds and two three centred (two electrons) B—H—B or hydrogen bridge bonds. These bonds are also known as banana bonds.

Q8.The calorific value of carbon is about ……. kcal.

•  7.8
•  15.6
•  47
•  94

Solution
Calorific value is the heat liberated by burning 1g fuel =94/12= 7.8 kcal /g. Heat of combustion of carbon = 94 kcal  

Q9.Boric acid is not used:

•  As an antiseptic
•  As a flux in soldering
•  In making optical glasses
•  In making enamels and pottery glazes

Solution
Rest all are uses of boric acid.

Q10. Commercially important ore of lead is

•  Haematite
•  Sphalerite
•  Siderite
• Galena

Solution
Galena is PbS.