CBSE Questions for Class 11 Engineering Chemistry Some P-Block Elements Quiz 12 - MCQExams.com

Which of the following is incorrect regarding the structural features of borax?
  • It has two tetrahedral and two triangular units
  • All the boron atoms are not in same hybrid state
  • Each boron atom of a pair is tetravalent
  • Only one boron atom has a lone pair of electrons
Consider the following reactions:

i)$$Cr_{2}O_{3}+2Al\rightarrow Al_{2}O_{3}+2Cr+heat$$
ii)$$Al_{2}O_{3}+2Cr\rightarrow Cr_{2}O_{3}+2Al+heat$$
iii)$$2Al+6NaOH\rightarrow 2Na_{3}AlO_{3}+3H_{2}$$

Out of these, the possible reactions are:
  • i and iii
  • ii and iii
  • i and ii
  • i , ii and iii
Order of stability of the ions of Ge, Sn and Pb is:
  • $$Ge^{2+} < Sn^{2+} < Pb^{2+}$$
  • $$Ge^{4+} < Sn^{4+} < Pb^{4+}$$
  • $$Sn^{4+} < Sn^{2+}$$
  • $$Pb^{2+} < Pb^{4+}$$
List -I                                                                           List -2
A. $$Al_{2}O_{3}$$                                                                Dimer
B. $$AlCl_{3}$$                                                                  Non-metal
C. $$B $$                                                                          Acidic
D.$$B_{2}O_{3}$$                                                                    Amphoteric 

The correct match is:
  • A-4, B-3, C-2, D-1
  • A-1, B-4, C-3, D-2 
  • A-2, B-3, C-4, D-1
  • A-4, B-1, C-2, D-3
Select the correct order with respect to acidic nature of the given compounds.
  • $$Al_{2}O_{3}< In_{2}O_{3}< Tl_{2}O< B_{2}O_{3}$$
  • $$Tl_{2}O< \, In_{2}O_{3}< Al_{2}O_{3}< B_{2}O_{3}$$
  • $$Al_{2}O_{3}< B_{2}O_{3}< \: In_{2}O_{3}< Tl_{2}O$$
  • $$Tl_{2}O< Al_{2}O_{3}< B_{2}O_{3}< \: In_{2}O_{3}$$
Which of the following statement is/are correct?
  • $$B_{2}H_{6}$$ is not an electron-deficient compound
  • Boron has an extremely high melting point because of the strong binding forces in the covalent polymer
  • $$BF_{3}$$ and $$BrF_{3}$$ molecules have different shapes
  • Ortho boric acid contains pyramidal $$BO_{3}^{-3}$$ units
In representative elements the ionization energy values generally decrease smoothly down the group. But in boron group the values show an erratic trend. This is mainly due to : 
  • increase in metallic nature down the group
  • inert pair effect in the heavier elements of the group
  • d-block contraction and lanthanide contraction affecting the values of later elements due to poor shielding by d and f electrons
  • the different type of packing in their crystalline structure
Which of the following have a three dimensional network structure?
  • $$\displaystyle\:SiO_{2}$$
  • $$\displaystyle\:(BN)_{5}$$
  • $$\displaystyle\:P_{4}(white)$$
  • $$\displaystyle\:CCl_{4}$$
Consider the following compound 
If hybridization of 'C' is $$sp$$ ($$s + px$$) and nodal plane of $$\pi$$-bond present between C and S is 'XY' plane then which of the following statement(s) is/are CORRECT regarding given information for above compound.

1200928_9311d2520eab4d5c8973bf131667dde1.PNG
  • $$\pi$$- bond between N and C atom is formed by sideways overlapping of $$p_y$$ orbitals
  • $$(2p_{\pi}$$ – $$3d_{\pi}$$) back bond between N and Si atom can be formed by ($$d_{xz} – p_z$$) orbital overlapping
  • $$\sigma$$- bond between N and Si atom is formed by $$sp^3$$ hybrid orbital of Si and $$sp_{x}$$ hybrid orbital of N atom. 
  • Six atoms of given compound are lying in same plane.
Which one of the following statements is incorrect about the structural properties of $$ BF_{3}$$?
  • The unsual shortness of $$B-F$$ bonds is due to $$p\pi - p\pi $$ interaction between $$B$$ and $$F$$ atoms
  • All the three $$B-F$$ bond lengths are equal
  • Double bond is delocalized giving three resonance structures.
  • Due to back bonding, $$BF_{3}$$ and $$BCl_{3}$$ are not isostructural molecules
The aqueous solution of 'A' is alkaline due to
  • the presence of $$Ca^{2+}$$ ions
  • the presence of $$H_{3}BO_{3}$$
  • hydrolysis of $$B_{4}O_{7}^{2-}$$
  • hydrolysis of $$CO_{3}^{2-}$$
Select the correct statements.
  • Oxides of boron $$(B_{2}O_3)$$ and silicon $$(SiO_{2})$$ are acidic in nature.
  • Oxides of aluminium $$(Al_{2}O_{3})$$ and gallium $$(Ga_{2}O_{3})$$ are amphoteric in nature.
  • Oxides of indium $$(In_{2}O_{3})$$ and thallium $$(Tl_{2}O_{3})$$ are basic in nature.
  • Oxides of germanium $$(GeO_{2})$$ and tin $$(SnO_{2})$$ are acidic in nature.
Alkyl substituted chlorosilane, $$R_{n}SiCl_{(4-n)}$$, on hydrolysis and then condensation polymerisation yields silicones. What is the value of n in the alkyl substituted chlorosilane used for the preparation of cross-linked silicone?
  • 1
  • 2
  • 3
  • 4
How many oxygen atoms are shared per $$ SiO_{4}$$ tetrahedral unit in mineral wollastonite $$[Ca_{3}(Si_{3}O_{9})]$$?
  • 2
  • 3
  • 1
  • 4
Silica reacts with $$Mg$$ to form a magnesium compound $$A$$. $$A$$ reacts with dilute $$HCl$$ and forms $$B$$. The compound $$B$$ is:
  • $$MgSiO$$
  • $$MgO$$
  • $$Mg{ Cl }_{ 2 }$$
  • $$Si{ Cl }_{ 4 }$$
The chain length of silicone polymer can be controlled by adding:
  • $$MeSiCl_{3}$$
  • $$Me_{2}SiCl_{2}$$
  • $$Me_{3}SiCl$$
  • $$Me_{4}Si$$
Which of the following oxides is acidic in nature?
  • $$B_{2}O_{3}$$
  • $$Al_{2}O_{3}$$
  • $$Ga_{2}O_{3}$$
  • $$In_{2}O_{3}$$
Ammonia gas is not prepared by :
  • reduction of sodium nitrite or sodium nitrate by the reaction of zinc dust and sodium hydroxide.
  • hydrolysis of calcium cyanamide.
  • heating ammoniumchloridewith slaked lime.
  • heating of $$(NH_{4})_{2}Cr_{2}O_{7}$$
In silicones, the maximum number of silicon atoms directly linked to an oxygen atom is :
  • 3
  • 4
  • 1
  • 2
Which among the following substances is not a component of the mixture used for glazing pottery?
  • Feldspar
  • Silica
  • Borax
  • Alumina
Which of the following does not react with cold water?
  • $$SiC$$
  • $$AIN$$
  • $$CaC_{2}$$
  • $$Al_{4}C_{3}$$
$$Me_3SiCl$$ is mixed with $$Me_2SiCl_2$$ to get a polymers called silicones of the type:
  • Both A and B
  • None of these
Which of following stability order is /are correct due to inert pair effect?
  • $$\displaystyle\:Hg^o >Hg^{2+}$$
  • $$\displaystyle\:Bi^{3+} < Bi^{5}$$
  • $$\displaystyle\:Pb^{2+} > Pb^{4+}$$
  • $$\displaystyle\:Fe^{2+} < Fe^{3+}$$
Among the following, the element which show inert-pair effect are:
  • $$\displaystyle\:Bi$$
  • $$\displaystyle\:Sn$$
  • $$\displaystyle\:Pb$$
  • $$\displaystyle\:C$$
The correct B --- F bond length follows the sequence :
  • $${ BF }_{ 3 }\quad <\quad { BF }_{ 2 }{ OH }\quad <\quad { BF }_{ 2 }{ NH }_{ 2 }\quad <\quad { B{ F }_{ 4 }^{ - } }$$
  • $${ BF }_{ 2 }{ NH }_{ 2 }\quad <\quad { BF }_{ 2 }{ OH }\quad <\quad { BF }_{ 3 }\quad <{ BF }_{ 4 }^{ - }$$
  • $${ { BF }_{ 3 } }\quad <\quad { BF }_{ 4 }^{ - }\quad <\quad { BF }_{ 2 }{ OH }\quad <\quad { BF }_{ 2 }{ NH }_{ 2 }$$
  • $${ BF }_{ 3 }\quad <\quad { BF }_{ 2 }{ NH }_{ 2 }\quad <{ BF }_{ 2 }{ OH }\quad <\quad { BF }_{ 4 }^{ - }$$
Microcosmic salt and borax are used in the identification of cations by dry tests. They are respectively :
  • $$Na{ BO }_{ 2 }$$ and $$Na{ PO }_{ 3 }$$
  • $$Na{ NH }_{ 4 }{ HPO }_{ 4 }.{ 4H }_{ 2 }O$$ and $${ Na }_{ 2 }{ B }_{ 4 }{ O }_{ 7 }.10{ H }_{ 2 }O$$
  • $$Na{ PO }_{ 3 }$$ and $$Na{ BO }_{ 2 }$$
  • $${ Na }_{ 2 }{ B }_{ 4 }{ O }_{ 7 }$$ and $$Na{ NH }_{ 4 }{ HPO }_{ 4 }$$
Read the following write-ups and answer the questions at the end of it. 
Silicons are synthetic polymers containing repeated $$R_{2}SiO$$ units. Since, the empirical formula is that of a ketone $$(R_{2}CO)$$, the name silicone has been given to these materials. Silicones can be made into oils, rubbery elastomers and resins. They find a variety of applications because of their chemical inertness, water repelling nature, heat- resistance and good electrical insulating property. Commercial silicon polymers are usually methyl derivatives and to a lesser extent phenyl derivatives and  are synthesised by the hydrolysis of $$R_{2}SiCl_{2}$$[R=methyl (Me) or phenyl (Ph)]

If we mix $$Me_{3}SiCl$$ with $$Me_{2}SiCl_{2}$$, we get silicones of the type:
  • both of the above
  • none of the above
The silicate anion in the mineral kinoite is a chain of three $$SiO_{4}$$ tetrahedra that share corners with adjacent tetrahedra. The mineral also contains $$Ca^{2+}$$ ions, $$Cu^{2+}$$ ions and water molecules in a 1:1:1 ratio. The mineral is represented as :
  • $$CaCuSi_{3}O_{10}H_{2}O$$
  • $$Ca_{2}Cu_{2}Si_{3}O_{10}H_{2}O$$
  • $$Ca_{2}Cu_{2}Si_{3}O_{10}2H_{2}O$$
  • none of these
($${Si_2O_5}$$)$${\displaystyle^{2n-}_{n}}$$ anion is obtained when :
  • no oxygen of a $${SiO^{4-}_{4}}$$ tetrahedron is shared with another $${SiO^{4-}_{4}}$$ tetrahedron
  • one oxygen of a $${SiO^{4-}_{4}}$$ tetrahedron is shared with another $${SiO^{4-}_{4}}$$ tetrahedron
  • two oxygen of a $${SiO^{4-}_{4}}$$ tetrahedron is shared with another $${SiO^{4-}_{4}}$$ tetrahedron
  • three oxygen of a $${SiO^{4-}_{4}}$$ tetrahedron is shared with another $${SiO^{4-}_{4}}$$ tetrahedron
$$Al + N_2 \xrightarrow {\triangle} (A) \xrightarrow {H_2O} (B) \xrightarrow {K_2HgI_4/OH^-} (D)$$ (brown ppt.)

What is $$(D)$$?
  • $$H_2N - Hg - Hg - I$$
  • $$H_2N - Hg - O - Hg - I$$
  • $$H_2N - O -Hg- Hg - I$$
  • $$H_2N - Hg - I - Hg - O$$
One natural source of atmospheric $$CO_2$$ is precipitation reaction such as the precipitation of silicates in the oceans:

$$Mg^{2+}(aq)+SiO_2(dispersed)+2HCO_3(aq)\rightarrow MgSiO_3(s)+2CO_2(g)+H_2O(l)$$

How many grams of magnesium silicate would be precipitated during the formation of $$100$$ L of $$CO_2$$ at $$30^oC$$ and $$775$$ torr? 
$$(Mg=24, Si=28, C=12, O=16)$$
  • $$102\ g$$
  • $$410 \ g$$
  • $$205\ g$$
  • $$51\ g$$
Borax in its crystal possess:
  • 3 tetrahedral unit
  • 2 tetrahedral and 2 planar triangular units
  • 3 tetrahedral and 2 planar triangular units
  • all tetrahedral units
Borax is converted into crystalline boron by the following steps:

$${Borax  \overset{X}{\rightarrow} H_3BO_3\overset{\Delta }{\rightarrow} B_2O_3\xrightarrow[\Delta ]{Y} B}$$
Then $$X$$ and $$Y$$ are respectively:
  • $$HCl, Mg$$
  • $$HCl, C$$
  • $$C, Al$$
  • $$HCl , Al$$
Select the correct statement(s) :
  • When Al is added to potassium hydroxide solution,hydrogen gas is evolved
  • $${H_2 Si F_6}$$ is formed when silica reacts with hydrogen fluoride followed by hydrolysis
  • Phosphine gas is formed when red phosphorus is heated with NaOH
  • ($${NH_4})_2 SO_4.FeSO_4.6H_2O $$ is called alums
One type of silicon adhesive uses a polymer that has two $$OH$$ groups left on the ends of the chain:
$$HO-Si(CH_3)_2[O-Si(CH_3)_2]_n-O-Si(CH_3)_2-OH$$
It has been found that this kind of polymer reacts easily with an organic-silicon molecule that contains acetate $$(CH_3COO)$$ group. Which of these three molecules $$CH_3COOSi(CH_3)_3$$,  $$(CH_3COO)_2Si(CH_3)_2$$, $$(CH_3COO)_3SiCH_3$$ would you choose to add to the hydroxy polymer in order to make a strong adhesive?
  • $$CH_3COOSi(CH_3)_3$$,
  • $$(CH_3COO)_2Si(CH_3)_2$$
  • $$(CH_3COO)_3SiCH_3$$
  • None of the above
Select correct statements:
  • Hydrides of $$B$$ and $$Si$$ are volatile and catch fire on exposure to air.
  • Oxides of $$B$$ and $$Si(B_2O_3$$ and $$SiO_2)$$ are acidic in nature.
  • Borates and silicates have tetrahedral $$BO_4$$ and $$SiO_4$$ structural units.
  • All the above are correct statements.
Select correct statement about stability of cations.
  • $$Ge^{4+} > Sn^{4+} > Pb^{4+}$$
  • $$Ge^{2+} < Sn^{2+} < Pb^{2+}$$
  • $$Pb^{2+} > Pb^{4+}, Sn^{4+} > Sn^{2+}$$
  • All the above are correct statements.
Silicone's :
  • are synthetic polymer containing repeating $$(R_2SiO)$$ units.
  • are formed by hydrolysis of $$R_2SiCl_2$$.
  • are natural occurring repeated $$(SiO_4)$$ units.
  • single $$R_2SiO$$ unit.
Silicone's are : 
  • synthetic polymers containing repeated $$R_2SiO$$ units.
  • silicates with common $$SiO_4$$ unit.
  • ketones with silyl group $$(SiH_3)$$ similar to alkyl $$(SiH_3)_2CO$$
  • Zircon (neso silicates)
The color imparted by Co(Il) compounds to glass is :
  • deep blue.
  • green.
  • yellow.
  • red.
Which is incorrect statement about silicons?
  • They are repeating units $$(SiO_4)$$ in silicates
  • They are synthetic polymers containing repeated $$R_2SiO$$ units
  • They are formed by hydrolysis of $$R_2SiCl_2$$
  • All the above are incorrect statements
Select correct statement(s) :
  • $$Si$$ uses all of its valence electrons in an $$sp^3$$-hybridization and crystallizes in an fcc structure similar to diamond.
  • Diamond is an electrical insulator, graphite is an electrical conductor but silicon is a semiconductor.
  • Most common silica is quartz.
  • All of the above are correct statements.
If we mix $$SiMe_3Cl$$ with $$SiMe_2Cl_2$$, we get silicone's of the type:
165021_5d65947ae1264057afae22fadcfeabac.png
  • both (a) and (b)
  • none of the above
$$Ca_2B_6O_{11}\xrightarrow {\Delta}[X]+CaCO_3+NaBO_2$$ (unbalanced equation) Which of the following is/are correct choice(s) for [X]?
  • The structure of anion of crystalline [$$X$$] has one boron atom $$sp^3$$ hybridized and other three boron atoms $$sp^2$$ hybridized
  • $$X$$ with $$NaOH_{(aq)}$$ gives a compound which on reaction with hydrogen peroxide in alkaline medium yields a compound used as the brightener in soaps
  • Hydrolysis of [$$X$$] with $$HCl$$ or $$H_2SO_4$$ yields a compound which on reaction with $$HF$$ gives fluoroboric acid
  • [$$X$$] on heating with chromium salts in oxidizing flame gives green colored bead
$$ B^{3+} $$ ion can not exist in aqueous solution because of its :
  • strong reducing ability
  • strong oxidizing ability
  • small size and large charge
  • large size and small charge
Aqueous solution of borax reacts with 2 mol of acids. This is because of?
  • Formation of 2 mol of $$B(OH)_{3}$$ only.
  • Formation of 2 mol of $$\left [B(OH)_{4} \right ]^{-}$$ only.
  • Formation of 1 mol each of $$B(OH)_{3}$$ and $$\left [B(OH)_{4} \right ]^{-}$$ only.
  • Formation of 2 mol each of $$\left [B(OH)_{4} \right ]^{-}$$ and $$B(OH)_{3}$$, of which $$\left [B(OH)_{4} \right ]^{-}$$ reacts with acid.
Borax is actually made of two tetrahedral and two triangular units joined together and should be 
written as : $$Na_{2}\:[B_{4}O_{5}(OH)_{4}].8H_{2}O$$.
Consider the following statements about borax:
Each boron atom has four B-O bonds
EAch boron atom has three B-O bonds
Two boron atoms have four B-O bonds while other two have three B-O bonds
Each boron atom has one-OH groups
Select correct statement(s) -
  • 1, 2
  • 2, 3
  • 3, 4
  • 1, 3
Identify the only 'INCORRECT' statement of the following.
  • B - O - B bonds in sodium peroxoborate are similar
  • B-O-B bonds in potassium trioborate are 3
  • Ortho borate ion is triangular plannar
  • B -O-B bonds in diborate ion is 1.
Identify the correct order of boiling point :
  • $$HF\,<\,HCl\,<\,HBr\,<\,HI$$
  • $$NH_3\,<\,PH_3\,<\,AsH_3\,<\,SbH_3$$
  • $$CH_4\,<\,SiH_4\,<\,GeH_4\,<\,SnH_4$$
  • $$H_2S\,<\,H_2Se\,<\,H_2Te\,<\,H_2O$$
The incorrect statements among the following are:
  • $$NCl_5$$ does not exist while $$PCl_5$$ does
  • Pb prefers to form tetravalent compounds
  • The three $$C-O$$ bond are not equal in the carbonate ion
  • Both $$O_2^+$$ and $$NO$$ are paramagnetic
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