has a composition intermediate between silicone oils and silicon rubbers.

is not related to any chemical.

each Si atom is surrounded by four O atoms and each oxygen atom is bonded to two Si atoms

one Si atom is bonded to two O atoms

there are double bonds between Si and O atoms

each Si atom is surrounded by two O atoms and each O is bonded to two Si atoms

MCQ Questions for Class 11 Engineering Chemistry Some P-Block Elements Quiz 5

Which involves breaking of covalent bonds?

0%
Boiling of $H_2S$
0%
Melting of $SiO_2$
0%
Melting of $KCN$
0%
Boiling of $CCl_4$

Explanation

Silica has a three-dimensional network structure. In silica, silicon is

$sp^3$ - hybridized and is thus linked to four oxygen atoms and each oxygen atom is linked to two silicon atoms forming a three-dimensional giant molecule as shown in figure. This three-dimensional network structure imparts stability to

$SiO_2$ crystal and hence a large amount of energy is required to break the crystal resulting in high melting point.
And melting of this breaks covalent bonds between molecules.

Elements of group

$14$ used in semiconductors are :

0%
$C, Si, Ge$
0%
$Si, Ge, Sn$
0%
$Si, Ge$
0%
$B, Si, Ge$

The colour of blue glass is due to the presence of oxide of :

0%
chromium
0%
cobalt
0%
gold
0%
silver

Which silicon compound is used as lubricant?

0%
Asbestos
0%
Silicone's
0%
Zeolites
0%
Mica

In casting of metal, silicon is used as :

0%
oxidizer
0%
semi conductor
0%
deoxidizer
0%
none of these

Which of the following has the highest first ionization energy?

0%
Lithium
0%
Beryllium
0%
Boron
0%
Carbon

Explanation

Carbon has the highest first ionization energy.
The order of the ionization energies is

$Li<Be<B<C$
On moving from left t right in a period, the ionization energy increases as the effective nuclear charge increases and the size decreases. The removal of electron becomes more and more difficult.

The great thermal and chemical stability of silicone's is attributed to high strength of :

0%
silicon-carbon bond.
0%
silicon-oxygen bond
0%
silicon-silicon bond
0%
carbon-carbon bond

Silly putty :

0%
is a silicone polymer.
0%
has a composition intermediate between silicone oils and silicon rubbers.
0%
is an asbestos.
0%
is not related to any chemical.

At room temperature the solid compound is :

0%
$CO_2$
0%
$SiO_2$
0%
$NO_2$
0%
$SO_2$

Explanation

Only

$SiO_2$ is solid all else are gases at room temperature.

Silicon is the _________ abundant element in the earth's crust.

0%
most
0%
2nd most
0%
3rd most
0%
none of these

Silicon exists only in the diamond structure due to tendency to form

$p\pi - p\pi$ bonds to itself.

0%
True
0%
False

Explanation

Silicon can not form

$p\pi-p\pi$ bond with itself. It exists in diamond cubic structure and forms sigma bonds with itself in

$sp^3$ hybridization

Silicone's are synthetic polymers containing repeated

$R_2SiO$ units.

0%
True
0%
False

Explanation

SILICONES: Organic polymers containing silicon in them are called as silicones. These are organosilicon polymers containing

$R_2SiO$ repeating units and empirical formula analogous to ketone

$(R_2CO)$ .
Alkyl substituted : These are formed by hydrolysis of alkyl chlorosilanes and their polymerisation. The alkyl or aryl substituted chlorosilanes are prepared by the reaction of Grignard reagent and silicon tetrachlorides.

State whether the given statement is true or false:

$Fe_2O_3$ and

$CuO$ impart green colour to the glass.

0%
True
0%
False

Number of isotopes of carbon is :

0%
$3$
0%
$4$
0%
$5$
0%
$6$

Explanation

Any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in the nucleus, or different atomic weights are called isotopes.

Number of isotopes of carbon are 3.They are

$C_6^{12}$ ,

$C_6^{13}$ and

$C_6^{14}$
Hence option A is correct.

Group

$14$ (carbon family) elements have the following properties:

0%
They are all network solids with octahedral network.
0%
Only $SiO_2$ is a network solid with tetrahedral coordination and is a giant molecules.
0%
$SnO_2$ and $PbO_2$ are amphoteric oxides.
0%
All oxides are acidic.

Explanation

Silica has a three-dimensional network structure. In silica, silicon is

$sp^3$ -hybridized and is thus linked to four oxygen atoms and each oxygen atom is linked to two silicon atoms forming a three-dimensional giant molecule as shown in figure.

All the elements of this group form oxides of the type

$MO_2$ out of which

$CO_2$ and

$SiO_2$ are acidic while

$GeO_2$ ,

$SnO_2$ and

$PbO_2$ are amphoteric.

Which have a giant covalent structure?

0%
Diamond
0%
$Si{O}_{2}$
0%
$Si{Cl}_{4}$
0%
${CO}_{2}$

Explanation

Diamond and

$SiO_2$ have a giant covalent structure.

Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples of giant covalent structures (lattices) of atoms. All the atoms in these structures are linked to other atoms by strong covalent bonds and so they have very high melting points.

Which of the following is most stable?

0%
$Sn^{2+}$
0%
$Ge^{2+}$
0%
$Si^{2+}$
0%
$Pb^{2+}$

Explanation

Option (D) is correct.

$Pb^{2+}$ is most stable.

The stability of

$+2$ oxidation state increases down the group due to inert pair effect.

$Pb^{2+}$ >

$Sn^{2+}$ >

$Ge^{2+}$ >

$Si^{2+}$

Thallium shows different oxidation states because :

0%
of its high reactivity.
0%
of inert pair of electrons.
0%
of its amphoteric nature.
0%
it is a transition metal.

Explanation

Hint: Thallium has electrons in d and f subshells which provide poor shielding.

Correct Answer: Option B

Explanation

$Thallium$ is a $p$ block element belonging to group $13$ and period $6$ .
Electronic configuration of $Thallium$ is $\left [ Xe \right ] 4f^{14} 5d^{10} 6s^{2} 6p^{1}$ .
$d$ and $f$ electrons of inner shells provide poor shielding, thus the attraction of the nucleus on the $s$ electrons of the outermost shell increases. This is called the inert pair effect.
Whereas, $s$ electrons provide strong shielding to $p$ electrons, thus making it easy for the $p$ electrons to be released.
Thus, although $Thallium$ shows $+3$ and $+1$ oxidation states, $+1$ is more common.

Boron compounds behave as Lewis acids because of their :

0%
acidic nature.
0%
covalent nature.
0%
ionic nature.
0%
vacant orbital.

On the addition of mineral acid to an aqueous solution of borax, the following compound is formed :

0%
boron hydride.
0%
ortho-boric acid.
0%
meta-boric acid.
0%
pyro-boric acid.

Explanation

Correct Answer: Option B

Explanation:

Treatment of borax with mineral acid is a process for extraction of boron.
The first product thus formed is tetraboric acid.
Tetraboric acid gets converted to orthoboric acid on treatment with water.
The equations of the reactions are as follows:

Hence, the correct answer is option $B.$

Select the correct order of acidic nature of non-metal oxide :

0%
$CO\, >\, CO_2$
0%
$CO_2\, >\, CO$
0%
$CO_2\, >\, SiO_2$
0%
$CO_2\, <\, SiO_2$

Explanation

1. Among the various oxides of same element, as the number of oxygen per element atom increases, the acidic nature of that oxide will be increased.

Hence

$CO_2\, >\, CO$ correct order.

2.Acidic character of oxide is directly proportional to oxidation state of the central atom.

Among the various oxides of different elements of the same group, as we move from top to bottom, the acidic nature will be decreased.

Hence

$CO_2\, >\, SiO_2$ is correct order.

Hence option B & C are correct.

The decrease in stability of higher oxidation states in p-block with increasing atomic number is due to :

0%
increase in bond energy on going down the group
0%
the reluctance of electrons of s-sub shell to participate in chemical bonding
0%
poor screening effect of d-orbitals
0%
none of the above

Which is likely to show inert pair effect?

0%
K
0%
Mg
0%
Al
0%
Pb

Which statement is correct with respect to the property of the elements with increase in atomic number in the carbon family?

0%
Their metallic character decreases
0%
The stability of +2 oxidation state increases
0%
Their ionization energy increases
0%
Their atomic size decreases

The ion(s) that act/s as oxidizing agent in solution is/ are :

0%
$Tl^+$ and $Al^{3+}$
0%
$B^{3+}$ and $Al^{3+}$
0%
$Tl^{3+}$ only
0%
$B^{3+}$ only

Explanation

The stability of lower oxidation state on moving down the group is increases due to inert pair pair effect.

Only

$Tl^{3+}$ is stable in +1 oxidation state than +3.

As we move down the group, the tendency of s-electrons of the valence shell to participate in bond formation decreases.

Hence,option C is correct.

Which of the following element does not show inert pair effect?

0%
Tl
0%
Pb
0%
Bi
0%
C

The balanced equation for the reaction when calcium phosphate is heated with a mixture of sand and carbon is given by:

0%
$2Ca_3(PO_4)_2 +6SiO_2 +10C \rightarrow 6CaSiO_3 +10CO +P_4$
0%
$2Ca_3(PO_4)_2 +4SiO_2 +15C \rightarrow 6CaSiO_3 +10CO +P_4$
0%
$2Ca_3(PO_4)_2 +6SiO_2 +6C \rightarrow 6CaSiO_3 +10CO +P_4$
0%
$2Ca_3(PO_4)_2 +5SiO_2 +10C \rightarrow 6CaSiO_3 +10CO +P_4$

Explanation

The balanced equation for the reaction when calcium phosphate is heated with a mixture of sand and carbon.

$2Ca_3(PO_4)_2 +6SiO_2 +10C \rightarrow 6CaSiO_3 +10CO +P_4$

The products are calcium silicate, carbon monoxide and phosphorous.

The stability of +1 oxidation state increases in the sequence:

0%
$Tl < In < Ga < Al$
0%
$Tl < Ga < In < Al$
0%
$Ga < In < AI < Tl$
0%
$Al < Ga < In < Tl$

Explanation

Explanation:

The inert pair effect is seen in the post-transition elements.

It is a phenomenon in which the electron pair of $s$ orbital remains inert.

Inert pair effect increases down the group.

Therefore, the stability of $+1$ oxidation state increases in the sequence

$Tl$ > $In$ > $Ga$ > $Al$ .

Hence, the correct answer is option $D$ .

Among the following substituted silanes the one which will give rise to cross-linked silicone polymer on hydrolysis is :

0%
$R_3SiCl$
0%
$R_4Si$
0%
$RSiCl_3$
0%
$R_2SiCl_2$

Explanation

Explanation:

Option A): On hydrolysis of $R_3SiCl$ , it forms monohydroxy silane derivative.

Option B): $R_4Si$ is inert to hydrolysis and can't undergo polymerization due to lack of $Cl$ group.

Option C): $RSiCl_3$ reacts with water to form hydroxide which on polymerization gives cross-linked silicone polymer.

$RSiCl_3$ + $3H_2O \rightarrow RSi{(OH)}_3 + 3HCl$

$RSi{(OH)}_3$ will give cross-linked silicone polymer on polymerization.

Option D): On hydrolysis, the $Cl$ gets replaced by $OH$ to form a dihydroxy silane derivative. This can lead to straight-chain polymerization.

Hence, the correct answer is option $C$ .

Which of the following has a giant covalent structure ?

0%
$PbO_{2}$
0%
$SiO_{2}$
0%
$NaCl$
0%
$AlCl_{3}$

Silicones have the general formula :

0%
${SiO_{4}}^{4-}$
0%
${Si_2O_{7}}^{6-}$
0%
$(R_2SiO)_n$
0%
${(SiO_3)_{n}}^{2-}$

Explanation

Organic polymers containing silicon in them are called as silicons. Silicons have general formula of

$R_2SiO$ , an empirical formula analogous to ketone

$(R_2CO)$ .

$CO_2$ and

$SiO_2$ is a solid or gas ?

0%
$CO_2$ gas and $SiO_2$ solid
0%
$CO_2$ solid and $SiO_2$ gas
0%
$CO_2$ gas and $SiO_2$ gas
0%
$CO_2$ solid and $SiO_2$ solid

Explanation

If you look at the crystal structure of silicon dioxide, you will see it is comprised of tetrahedra (one silicon surrounded by 4 oxygen atoms) and these tetrahedra are in turn connected to each other, and subsequently form a 2-dimensional network which is large enough to make this substance a solid. The intermolecular forces within

$CO_2$ are very weak, only comprised of London dispersion forces, thereby allowing for

$CO_2$ to exist as a gas rather than a liquid or solid under standard conditions.

$SiO_2$ on the other hand, has more of a metallic character since, silicon is a metalloid. The greater the ionic/metallic character of the substance, the greater the intermolecular forces will be. In addition to this,

$SiO_2$ has a highly crystalline shape, allowing for maximum interaction between the atoms to allow for a rigid and unwavering shape, thereby allowing

$SiO_2$ to form rigid bonds in a crystalline form.

In silicon dioxide :

0%
one Si atom is bonded to two O atoms
0%
there are double bonds between Si and O atoms
0%
each Si atom is surrounded by four O atoms and each oxygen atom is bonded to two Si atoms
0%
each Si atom is surrounded by two O atoms and each O is bonded to two Si atoms

Explanation

Hint: Silicon does not form stable $\pi$ bonds.

Explanation

· $Silicon \ dioxide$ is an amorphous covalent solid and is acidic in nature

· Unlike $CO_{2}, SiO_{2}$ does not exist in the form of a gas.

· This is because $SiO_{2}$ does not form stable $\pi$ bonds.

· The attraction between nuclei of $Silicon$ and $Oxygen$ atoms is unable to compensate for the repulsion between the electron clouds of the atoms. This makes $O=Si=O$ bonding very unstable.

Therefore,

$SiO_{2}$ exists in the form of a chain covalent network where each

$Silicon$ atom is attached to four

$Oxygen$ atoms by single bonds

Correct Option : $C$ .

The type of glass used in making lenses and prisms is :

0%
A flint glass
0%
Jena glass
0%
Pyrex glass
0%
Quartz glass

Galena is a important mineral of _____.

0%
lead
0%
germanium
0%
carbon
0%
tin

The building units of various crystalline forms of boron are:

0%
$B_{12}$ icosahedral units
0%
$B_4$ tetrahedral units
0%
$B_6$ octahedral units
0%
$B_6$ cubical units

Explanation

The building units of various crystalline forms of boron are

$B_{12}$ icosahedral units.Icosahedron is a three dimensional space formed bt twenty equilateral triangles meeting at twelve vertices.All the twelve vertices of icosahedron are occupied by boron atoms to constitute

$B_{12}$ unit.

Glass or silica soluble in:

0%
$HClO_4$
0%
$HF$
0%
aqua-regia
0%
$H_2SO_4$

Which of the following pair consists of only network solid?

0%
$SiO_2, CO_2$
0%
Graphite, $SO_2$
0%
$P_4O_{10}, P_4O_6$
0%
Diamond , $SiO_2$

Explanation

A network solid or covalent network solid is a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal may be considered a macromolecule.
So in Diamond , $SiO_2$ atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal may be considered a macromolecule.
Hence option D is correct.

Assertion(A):

$Be$ forms

$[BeF_4]^{2-}$ , but

$Al$ forms

$[AlF_6]^{3-}$ .

Reason(R): $Be$ does not have d-orbitals in the valence shell but

$Al$ has.

0%

If both (A) and (R) are correct and (R) is the correct explanation of (A).
0%
If both (A) and (R) are correct, but (R) is not the correct explanation of (A).
0%
If (A) is correct, but (R) is incorrect.
0%

If (A) is incorrect, but (R) is correct.

Boron of highest purity (99.9%) is obtained by:

0%
reduction of $B_2 O_3$ by $Mg$
0%
electrolysis of fused tetrafluoroborates $(KBF_4)$ in molten $KF$
0%
reduction of $BCl_3$ with $H_2$ at 1270 $K$
0%
thermal decomposition of boranes at 1173 $K$

Among the following which elements have its lower oxidation state more stable than their higher oxidation state?

0%
$Pb$
0%
$Sn$
0%
$Tl$
0%
$Sb$

Explanation

In group 13, the characteristic group oxidation state of

$+ 3$ is known but the

$+ 1$ state gets progressively stabilized on going down the group. It is particularly favored by

$Tl$ . This is a consequence of the so called 'inert pair effect' which also accounts for the stability of the dipositive oxidation states of

$Sn$ and

$Pb$ and tripositive state of

$Bi$ .

Statement - I: Silicones are very inert polymers.

Statement - II: Both Si-O and Si-C bond energies are very high.

Read the above statements and choose the correct option regarding it.

0%
Statement-I is true, Statement-II is true ; Statement-II is correct explanation for Statement-I.
0%
Statement-I is true, Statement-II is true ; Statement-II is not a correct explanation for Statement-I.
0%
Statement-I is true, Statement-II is false.
0%
Statement-I is false, Statement-II is true.

Explanation

Option (A) is correct.

Silicones are very inert polymers.Both

$Si-O$ and

$Si-C$ bond energies are very high.
The bond energy of Si-O bond is 502 kJ/mol.
The chemical inertness is also due to stable silica like arrangement of Si-O-Si-O-Si.

Silicones are organosilicon polymers containing Si-O-Si linkages.

Which of the following silk fibre is soft, lustrous and elastic?

0%
Tassar silk
0%
Mooga silk
0%
Kosa silk
0%
Mulberry silk

Explanation

Option

$(D)$ is correct.

Mulberry silk fibre is soft, lustrous and elastic. It is most common silk fibre and can be dyed in beautiful colours.

Crystalline boron in small amounts may be obtained by :

0%
Reducing $BCl_3$ with $H_2$
0%
pyrolysis of $BI_3$
0%
thermal decomposition of diborane
0%
all of these

Statement -1 :

$PbO_2$ is an oxidising agent and reduced to PbO.
Statement - 2 : Stability of Pb (II) > Pb (IV) on account of inert pair effect.

0%
Statement - l is True, Statement - 2 is True; Statement - 2 is a correct explanation for Stetement - l.
0%
Statement - 1 is True. Statement - 2 is True; Statement - 2 is NOT a correct explanation for Statement - l
0%
Statement - l is True, Statement - 2 is False
0%
Statement - l is False, Statement - 2 is True

Explanation

Statement -1 :

$PbO_2$ is an oxidising agent and reduced to

$PbO$ .

$Pb(IV)$ in

$PbO_2$ gains electrons to form

$Pb(II)$ in

$PbO$ . Hence it is an oxidizing agent

Statement - 2 : Stability of

$Pb (II) > Pb (IV)$ on account of the inert pair effect.

The inert pair effect is the tendency of the electrons in the outermost atomic s-orbital to remain un-ionized or unshared in compounds of post-transition metals. That is the reason

$PbO_2$ acts as an oxidising agent and readily reduces to

$PbO$ .

The number of possible isomers for disubstituted borazine,

$B_3 N_3 H_4 X_2$ is:

0%
3
0%
4
0%
6
0%
2

Amorphous boron on burning in air forms :

0%
$B(OH)_3$
0%
mixture of $B_2O_3$ and $BN$
0%
only $B_2O_3$
0%
only $BN$

Explanation

Amorphous boron on burning in the air gives a mixture of boron trioxide and boron nitride. Boron burns with a brilliant flame in oxygen.

The reaction can be given as follow:

$4B + 3O_{2} \rightarrow 2B_{2}O_{3}$

$2B + N_{2} \rightarrow 2BN$

The butter of tin is represented by:

0%
$SnCl_2.\, 5H_2O$
0%
$SnCl_2$
0%
$SnCl_4$
0%
$SnCl_4.\, 5H_2O$

Explanation

Tin(IV) chloride pentahydrate is butter of tin. It is represented as

$[SnCl_{4}\left( {H}_{2}O\right) _{2}]\cdot 3{H}_{2}O$ or

$SnCl_4.5H_2O$ .

Amorphous boron of 95% to 98% purity is obtained by:

0%
heating $B_2 O_3$ with $H_2$
0%
heating $B_2O_3$ with $Mg$ or $Na$ at high temperature
0%
heating $KBF_4$ with $Na$ or $K$
0%
heating $BBr_3$ with $H_2$ in presence of a catalyst

What will happen if boron trifluoride is kept in moist air?

0%
It will strongly fumes
0%
It will partially hydrolysed
0%
It will completely hydrolysed
0%
None of these

Explanation

In moist air it strongly fumes but it is partially hydrolysed by excess of water.

$4BF_3 + 6H_2O \rightarrow 3H_3O^{+} + 3BF_4^{-} + B(OH)_3$

$BF_3$ is a colourless gas.

CBSE Questions for Class 11 Engineering Chemistry Some P-Block Elements Quiz 5 - MCQExams.com

0:0:1

Practice Class 11 Engineering Chemistry Quiz Questions and Answers

CBSE Questions for Class 11 Engineering Chemistry Some P-Block Elements Quiz 5 - MCQExams.com

0:0:1

Practice Class 11 Engineering Chemistry Quiz Questions and Answers

Support mcqexams.com by disabling your adblocker.