Topic: The p-Block Elements (Test 1)



Topic: The p-Block Elements
Q.1
Silicon has a strong tendency to form polymers like silicones. The chain length of silicone polymer can be controlled by adding
A. Me2Si Cl2
B. SiCl
C. MeSiCl3
D. Me4Si
Answer : Option B
Explaination / Solution:

SiCl has only one Cl and (can react once) to forms only dimer thus it is used as chain controlling agent (terminate the polymerisation process).

Workspace
Report
Q.2
The maximum covalency of nitrogen is
A. Eight
B. Five
C. Four
D. Six
Answer : Option C
Explaination / Solution:

N has maximum covalency of 4 since only four (one s and three p) orbitals are available for bonding. d orbitals are not available for bonding.

Workspace
Report
Q.3
Ammonia act as a Lewis base because nitrogen has
A. None of these
B. 3 electrons in the outermost shell
C. Bond pair of electrons
D. Lone pair of electrons
Answer : Option D
Explaination / Solution:

NH3has one lone pair of electrons therefore can act as Lewis base.
Workspace
Report
Q.4
Regular use of which of the following fertilizers increases the acidity of the soil?
A. Potassium nitrate
B. Superphosphate of lime
C. Ammonium sulphate
D. Urea
Answer : Option C
Explaination / Solution:

Ammonium sulphate addition increases acidity in the soil. In the presence of water and oxygen in the soil, ammonium and sulfate are decomposed by naturally occurring microbes. During this process, acids are released into the soil, along with nitrogen and sulfur compounds.

Workspace
Report
Q.5
Which of the following is an amphoteric oxide?
A. Cr2O3
B. Cl2O7
C. V2O5
D. SnO2
Answer : Option A
Explaination / Solution:

Higher oxidation state oxides are acidic while lower oxidation state oxides are basic. Intermediate oxidation state oxides are amphroteric.

Workspace
Report
Q.6
Which of the following oxides reacts with both HCl and NaOH?
A. CO2
C. N2O5
Answer : Option B
Explaination / Solution:

ZnO is an amphroteric oxide.

Workspace
Report
Q.7
Xenondifluoride is
A. Pyramidal
B. Linear
C. Angular
D. Trigonal
Answer : Option B
Explaination / Solution:

CN=0.5(V+M-C+A) For XeF_2 CN = 5 so shape will be linear and structure will be trigonal pyramidal.

Workspace
Report
Q.8
One mole of magnesium nitride on the reaction with an excess of water gives:
A. two moles of nitric acid
B. one mole of nitric acid
C. two moles of ammonia
D. one mole of ammonia
Answer : Option C
Explaination / Solution:

 on hydrolysis roduces two moles of ammonia.

Workspace
Report
Q.9
As we move from B to Al in the p-block elements the sum of the first three ionisation enthalpies
A. considerably decreases
B. remains the same
C. increases
D. slightly decreases
Answer : Option A
Explaination / Solution:

On moving from B to Al size of the atom increases. So ionisation enthalpy decreases. Thus as we move from B to Al in the p-block elements the sum of the first three ionisation enthalpies considerably decreases.
This is the reason aluminium forms Al3+ ion.

Workspace
Report
Q.10
Silicon is the second most abundant element on the earth’s crust and is a component of
A. ceramics
B. glass wool
C. flux for soldering metals
D. antiseptic materials
Answer : Option A
Explaination / Solution:

Si is the most imp component of ceramics, which is comprised of metal, non-metal, or metalloids held by ionic or covalent bond.

Workspace
Report