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

Which involves breaking of covalent bonds?
  • Boiling of $$H_2S$$
  • Melting of $$SiO_2$$
  • Melting of $$KCN$$
  • Boiling of $$CCl_4$$
Elements of group $$14$$ used in semiconductors are :
  • $$C, Si, Ge$$
  • $$Si, Ge, Sn$$
  • $$Si, Ge$$
  • $$B, Si, Ge$$
The colour of blue glass is due to the presence of oxide of :
  • chromium
  • cobalt
  • gold
  • silver
Which silicon compound is used as lubricant?
  • Asbestos
  • Silicone's
  • Zeolites
  • Mica
In casting of metal, silicon is used as :
  • oxidizer
  • semi conductor
  • deoxidizer
  • none of these
Which of the following has the highest first ionization energy?
  • Lithium
  • Beryllium
  • Boron
  • Carbon
The great thermal and chemical stability of silicone's is attributed to high strength of :
  • silicon-carbon bond.
  • silicon-oxygen bond
  • silicon-silicon bond
  • carbon-carbon bond
Silly putty :
  • is a silicone polymer.
  • has a composition intermediate between silicone oils and silicon rubbers.
  • is an asbestos.
  • is not related to any chemical.
At room temperature the solid compound is :
  • $$CO_2$$
  • $$SiO_2$$
  • $$NO_2$$
  • $$SO_2$$
Silicon is the _________ abundant element in the earth's crust.
  • most
  • 2nd most
  • 3rd most
  • none of these
Silicon exists only in the diamond structure due to tendency to form $$p\pi - p\pi$$ bonds to itself.
  • True
  • False
Silicone's are synthetic polymers containing repeated $$R_2SiO$$ units.
  • True
  • False
State whether the given statement is true or false:

$$Fe_2O_3$$ and $$CuO$$ impart green colour to the glass.
  • True
  • False
Number of isotopes of carbon is :
  • $$3$$
  • $$4$$
  • $$5$$
  • $$6$$
Group $$14$$(carbon family) elements have the following properties:
  • They are all network solids with octahedral network.
  • Only $$SiO_2$$ is a network solid with tetrahedral coordination and is a giant molecules.
  • $$SnO_2$$ and $$PbO_2$$ are amphoteric oxides.
  • All oxides are acidic.
Which have a giant covalent structure?
  • Diamond
  • $$Si{O}_{2}$$
  • $$Si{Cl}_{4}$$
  • $${CO}_{2}$$
Which of the following is most stable?
  • $$Sn^{2+}$$
  • $$Ge^{2+}$$
  • $$Si^{2+}$$
  • $$Pb^{2+}$$
Thallium shows different oxidation states because :
  • of its high reactivity.
  • of inert pair of electrons.
  • of its amphoteric nature.
  • it is a transition metal.
Boron compounds behave as Lewis acids because of their :
  • acidic nature.
  • covalent nature.
  • ionic nature.
  • vacant orbital.
On the addition of mineral acid to an aqueous solution of borax, the following compound is formed :
  • boron hydride.
  • ortho-boric acid.
  • meta-boric acid.
  • pyro-boric acid.
Select the correct order of acidic nature of non-metal oxide :
  • $$CO\, >\, CO_2$$
  • $$CO_2\, >\, CO$$
  • $$CO_2\, >\, SiO_2$$
  • $$CO_2\, <\, SiO_2$$
The decrease in stability of higher oxidation states in p-block with increasing atomic number is due to :
  • increase in bond energy on going down the group
  • the reluctance of electrons of s-sub shell to participate in chemical bonding
  • poor screening effect of d-orbitals
  • none of the above
Which is likely to show inert pair effect?
  • K
  • Mg
  • Al
  • Pb
Which statement is correct with respect to the property of the elements with increase in atomic number in the carbon family?
  • Their metallic character decreases
  • The stability of +2 oxidation state increases
  • Their ionization energy increases
  • Their atomic size decreases
The ion(s) that act/s as oxidizing agent in solution is/ are :
  • $$Tl^+$$ and $$Al^{3+}$$
  • $$B^{3+}$$ and $$Al^{3+}$$
  • $$Tl^{3+}$$ only
  • $$B^{3+}$$ only
Which of the following element does not show inert pair effect?
  • Tl
  • Pb
  • Bi
  • C
The balanced equation for the reaction when calcium phosphate is heated with a mixture of sand and carbon is given by:
  • $$2Ca_3(PO_4)_2 +6SiO_2 +10C \rightarrow 6CaSiO_3 +10CO +P_4$$
  • $$2Ca_3(PO_4)_2 +4SiO_2 +15C \rightarrow 6CaSiO_3 +10CO +P_4$$
  • $$2Ca_3(PO_4)_2 +6SiO_2 +6C \rightarrow 6CaSiO_3 +10CO +P_4$$
  • $$2Ca_3(PO_4)_2 +5SiO_2 +10C \rightarrow 6CaSiO_3 +10CO +P_4$$
The stability of +1 oxidation state increases in the sequence:
  • $$Tl < In < Ga < Al$$
  • $$Tl < Ga < In < Al$$
  • $$Ga < In < AI < Tl$$
  • $$Al < Ga < In < Tl$$
Among the following substituted silanes the one which will give rise to cross-linked silicone polymer on hydrolysis is :
  • $$R_3SiCl$$
  • $$R_4Si$$
  • $$RSiCl_3$$
  • $$R_2SiCl_2$$
Which of the following has a giant covalent structure ?
  • $$PbO_{2}$$
  • $$SiO_{2}$$
  • $$NaCl$$
  • $$AlCl_{3}$$
Silicones have the general formula :
  • $${SiO_{4}}^{4-}$$
  • $${Si_2O_{7}}^{6-}$$
  • $$(R_2SiO)_n$$
  • $${(SiO_3)_{n}}^{2-}$$
 $$CO_2$$ and $$SiO_2$$ is a solid or gas ?
  •  $$CO_2$$ gas  and $$SiO_2$$   solid
  •  $$CO_2$$  solid  and $$SiO_2$$  gas
  •  $$CO_2$$  gas and $$SiO_2$$  gas
  •  $$CO_2$$   solid  and $$SiO_2$$  solid
In silicon dioxide :
  • one Si atom is bonded to two O atoms
  • there are double bonds between Si and O atoms
  • each Si atom is surrounded by four O atoms and each oxygen atom is bonded to two Si atoms
  • each Si atom is surrounded by two O atoms and each O is bonded to two Si atoms
The type of glass used in making lenses and prisms is :
  • A flint glass
  • Jena glass
  • Pyrex glass
  • Quartz glass
Galena is a important mineral of _____.
  • lead
  • germanium
  • carbon
  • tin
The building units of various crystalline forms of boron are:
  • $$B_{12}$$ icosahedral units
  • $$B_4$$ tetrahedral units
  • $$B_6$$ octahedral units
  • $$B_6$$ cubical units
Glass or silica soluble in:
  • $$HClO_4$$
  • $$HF$$
  • aqua-regia
  • $$H_2SO_4$$
Which of the following pair consists of only network solid?
  • $$ SiO_2, CO_2 $$
  • Graphite, $$ SO_2 $$
  • $$ P_4O_{10}, P_4O_6 $$
  • Diamond , $$ SiO_2 $$
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.
  • If both (A) and (R) are correct and (R) is the correct explanation of (A).
  • If both (A) and (R) are correct, but (R) is not the correct explanation of (A).
  • If (A) is correct, but (R) is incorrect.
  • If (A) is incorrect, but (R) is correct.

Boron of highest purity (99.9%) is obtained by:
  • reduction of $$B_2 O_3$$ by $$Mg$$
  • electrolysis of fused tetrafluoroborates $$(KBF_4)$$ in molten $$KF$$
  • reduction of $$BCl_3$$ with $$H_2$$ at 1270 $$K$$
  • thermal decomposition of boranes at 1173 $$K$$
Among the following which elements have its lower oxidation state more stable than their higher oxidation state?
  • $$Pb$$
  • $$Sn$$
  • $$Tl$$
  • $$Sb$$

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.
  • Statement-I is true, Statement-II is true ; Statement-II is correct explanation for Statement-I.
  • Statement-I is true, Statement-II is true ; Statement-II is not a correct explanation for Statement-I.
  • Statement-I is true, Statement-II is false.
  • Statement-I is false, Statement-II is true.
Which of the following silk fibre is soft, lustrous and elastic?
  • Tassar silk
  • Mooga silk
  • Kosa silk
  • Mulberry silk
Crystalline boron in small amounts may be obtained by :
  • Reducing $$BCl_3$$ with $$H_2$$
  • pyrolysis of $$BI_3$$
  • thermal decomposition of diborane
  • 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.
  • Statement - l is True, Statement - 2 is True; Statement - 2 is a correct explanation for Stetement - l.
  • Statement - 1 is True. Statement - 2 is True; Statement - 2 is NOT a correct explanation for Statement - l
  • Statement - l is True, Statement - 2 is False
  • Statement - l is False, Statement - 2 is True
The number of possible isomers for disubstituted borazine,$$B_3 N_3 H_4 X_2$$ is:
  • 3
  • 4
  • 6
  • 2
Amorphous boron on burning in air forms :
  • $$B(OH)_3$$
  • mixture of $$B_2O_3$$ and $$BN$$
  • only $$B_2O_3$$
  • only $$BN$$
The butter of tin is represented by:
  • $$SnCl_2.\, 5H_2O$$
  • $$SnCl_2$$
  • $$SnCl_4$$
  • $$SnCl_4.\, 5H_2O$$
Amorphous boron of 95% to 98% purity is obtained by:
  • heating $$B_2 O_3$$ with $$H_2$$
  • heating $$B_2O_3$$ with $$Mg$$ or $$Na$$ at high temperature
  • heating $$KBF_4$$ with $$Na$$ or $$K$$
  • heating $$BBr_3$$ with $$H_2$$ in presence of a catalyst
What will happen if boron trifluoride is kept in moist air?
  • It will strongly fumes
  • It will partially hydrolysed
  • It will completely hydrolysed
  • None of these
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