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Earn 100

Define Pyrosilicates.

Important Questions on p-Block Elements - I

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Example of a three-dimensional silicate is :
 
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The gas evolved on heating CaF2 and SiO2 with concentrated H2SO4, on hydrolysis gives a white gelatinous precipitate. The precipitate is:
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Among the following substituted silanes, the one which will give rise to cross-linked silicone polymer on hydrolysis is:
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An allotrope of carbon which exhibits only two types of C-C bond distance of 143.5 pm and 138.3 pm, is
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A tin chloride Q undergoes the following reactions (not balanced)

Q+Cl-X

Q+Me3NY

Q+CuCl2Z+CuCl

X is a monoanion having pyramidal geometry. Both Y and Z are neutral compounds. Choose the correct option(s).
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Identify the correct statements from the following:

a) Silicones are hydrophobic in nature. 

b) The repeating unit in silicones is

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c) In a C60 molecule, twenty C6 rings and twelve C5 rings are present. 

d) Dehydration of formic acid by concentrated H2SO4 at 100oC gives CO2

e) The distance between two layers in graphite is 34 pm

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Zeolites are shape selective structures because of
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Identify the correct statements from the following:
(a) CO2g is used as a refrigerant for ice cream and frozen food.
(b) The structure of C60 contains twelve six-membered carbon rings and twenty-five membered carbon rings.
(c) ZSM5, a type of zeolite, is used to convert alcohols into gasoline.
(d) CO is a colourless and odourless gas.
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Among the following substituted silanes, the one which will give rise to cross linked silicone polymer on hydrolysis is?
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Match the items in Column I with its main use listed in Column II:
 
  Column I   Column II
A Silica gel i. Transistor
B Silicon ii. Ion-exchanger
C Silicone iii. Drying agent
D Silicate iv. Sealant
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What product is formed when HF reacts with glass?
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Identify the incorrect statements from the following
I. Tin in +2 state acts as reducing agent while lead in +4 state acts as strong oxidising agent.
II. Silicon exists as both SiF62- and SiCl62- forms.
III. The hybridisation of carbon in fullerene is sp3.
IV. Among Ge, Sn and Pb lowest melting point is for Sn.
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Si reacts with CH3Cl at 573 K in the presence of Cu powder to form methyl substituted chlorosilanes. Among the given methyl substituted chlorosilanes, whose yield is minimum?
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Correct statements among regarding silicones are:
(a) They are polymers with hydrophobic character.
(b) They are biocompatible.
(c) In general, they have high thermal stability and low dielectric strength.
(d) Usually, they are resistant to oxidation and used as greases.

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Identify the correct statements
I) Germanium exists only in traces.
II) The order of electronegativity of Si, Ge, Sn is Sn>Ge>Si
III) All group 14 elements are available in solid state
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The basic structural unit of feldspar, zeolites mica, and asbestos is: