NEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2113
Discuss the pattern of variation in the oxidation states
of B to Ti Answer:
Element
| read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2114How can you explain higher stability of BCl3 as
compared to TlCl3? Answer: Boron exhibits only +3 oxidation state. So, it forms BCl3,
a stable compound. On moving down the group, the inert pair effect becomes
more and more pronounced therefo... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2115Why does Boron trifluride behave as a Lewis acid? Answer: BF3 being electron deficient, is a strong Lewis
acid. It reacts with Lewis bases easily to complete the octet around boron.
HINT: Lewis acids have a tendency to except electrons,... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2116Explain what happens when boric acid is heated? Answer: Boric acid, on heating loses water in three different temperatures
ultimately giving boron trioxide.
... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2117Suggest a reason as to why CO is poisonous? Answer: Carbon monoxide reacts with hemoglobin and form a stable
compound carboxyhemoglobin is 300 times more stable than oxyhemoglobin.
Formation of carboxyhemoglobin reduces the oxygen carrying ca... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2118Write the reaction of justify amphoteric nature of
aluminium. Answer: As dissolves both in acids and alkalies evolving
dihydrogen and thus, shows amphoteric nature.
... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2119Write the resonance structures of and Answer: Resonance structure of ion:
Resonance structure of ion:
... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2120Suggest reason why the B -----F bond lengths in BF3
(130 pm) and (143
pm) differ? Answer: In BF3, boron is sp2 hybridized. It has a
vacant 2p-orbital.Each fluorine in BF3 has completely filled
unutilized 2p-orbitals. Since, both of these... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2121How is excessive content of CO2 responsible for
global warming? Answer: CO2 is a green house gas. About 75% of the
solar energy reaching the earth is absorbed by the earth’s surface. The rest
of the heat radiates back to the atmosphere. But ... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2122Explain why is there a phenomenal decrease in ionization
enthalpy from carbon to silicon? Answer: As we move from carbon to silicon atomic size increases.
i.e., The distance between the outermost electron and nucleus increases. Thus
this ele... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2123How would you explain the lower atomic radius of Ga as
compared to aluminium? Answer: Electronic configuration of Al and Ga are as
The screening tendency of d-electrons is poor. Thus, on
moving from Al to Ga, shielding effect of 10d-electr... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2124What are allotrops? Sketch the structure of allotrops of
carbon mamely diamond and graphite. What is the impact of structure on
physical properties of two allotrops? Answer: The phenomenon of existence of an element in two or more
forms whic... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2125What do you understand by
(a) Inert pair
effect
(b) Allotropy
(c) Catenation? Answer: (a) Inert pair
effect: it is defined as the tendency of s- elections to remain togeth... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2126Draw the structures of BCl3. NH3 and AlCl3 (dimer). Answer:
... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2127Give reason for the following.
CCl4 is immiscible in water, whereas SiCl4
is easily hydrolyzed. Answer: Carbon tetrachloride (CCl4) is a covalent
compound while H2O is a polar compound and CCl4 does
not form H - bond with water molecule. ... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2128Give reason for the following.
Carbon has a strong tendency for catenation as compared to
silicon. Answer: The catenation is maximum in carbon and decreases down the
group. With increase in atomic size, electronegativity decrease, and due to... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2129Explain the following.
CO2 is a gas whereas SiO2 is a
solid. Answer: CO2 has a linear structure. Its dipole moment is zero. It
is believed that CO2 molecule is a resonance hybrid of following structures
sp hybridised
... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2130Explain the following.
Boron does not exist as B3+ ion. Answer: Due to small size of Boron, the sum of its first three
ionization enthalpies is very high. This prevents it to form +3 ions and
forces it to form only covalent compound. That’s ... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2131PbX2 is more stable than PbX4. Answer: Due to inert pair effect, Pb in + 2 oxidation state is
more stable than in + 4 oxidation state, hence, PbX2 is more
stable than PbX4.... read moreNEET - Grade 11 - Chemistry - The p-block elements - Study ref# 2132Carbon shows catenation property but lead does not. Answer: Due to inert pair effect TI in +1 oxidation state is more
stable than that of +3 oxidation state. Therefore, TI(NO3)3
acts as an oxidizing agent.... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9814On addition of conc.to a chloride salt,
colourless fumes are evolved but in case of iodide salt, violet fumes come
out. This is because
(a) reduces to HI to I2
(b) HI of violet colou... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9815Which of the following elements can be
involved in pπ – dπ bonding?
(a) Carbon
(b) Nitrogen
(c) Phosphorus
(d) Boron Answer: (c) Among given four elements i.e.,
carbon, nitrogen, phosphorus and boron. Only phosphorus has v... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9816Which of the following pairs of ions are
isoelectronic and isostructural?
(a)
(b)
(c) read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9817Affinity for hydrogen decreases in the
group from fluorine to iodine. Which of the halogen acids should have highest
bond dissociation enthalpy?
(a) HF
(b) HCI
(c) HBr
(d) HI Answer: read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9818On heating with concentrated NaOH
solution in an inert atmosphere of CO2, white phosphorus gives a
gas. Which of the following statement is incorrect about the gas?
(a) It is highly poisonous and has smell
like rotten fish.
(b) It’solu... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9819Which of the following acids form three
series of salts?
(a)
(b)
(c)
(d) read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9820Maximum covalency of nitrogen is ……….. .
(a) 3
(b) 5
(c) 4
(d) 6 Answer: (c) Maximum covalency of nitrogen is 4 in
which one electron is made available by s-orbital and 3 electrons are made
available by p orbitals. H... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9821A brown ring is formed in the ring test
for ion. It is due to the
formation of
(a)
(b)
(c) read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9822Which of the following is not tetrahedral
in shape?
(a)
(b)
(c)
(d) read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9823In the preparation of compounds of Xe,
Bartlett had taken as a base
compound. This is because
(a) both O2 and Xe have same
size.
(b) both O2 and Xe have same
electron gain enthalpy.
(c) both O2 and Xe have almost
same ioni... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9824Which of the following is isoelectronic
pair?
(a)
(b)
(c)
(d) read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9825Which of the following statements are
correct?
(a) All the three N – O bond lengths in are equal.
(b) All P – Cl bond lengths in PCl5
molecule in gaseous state are equal.
(c) P4 molecule in white
phosphorus have regular strain there... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9826Which of the following statements are
correct?
(a) S – S bond is present in
(b) In peroxosulphuric acid Sulphur is in +6
oxidation state
(c) Iron powder along with and K2O is
used as catalyst in the preparation of NH3 by Haber’s ... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9827In the preparation of by contact process, why
is not absorbed directly
in water to form? Answer: In contact proces... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9828Write a balanced chemical equation for
the reaction showing catalytic oxidation of by atmospheric oxygen. Answer: Ammonia () on catalytic by
... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9829In, phosphorus is in hybridized state but
all its five bonds are not equivalent. Justify your answer with reason. Answer: It has trigonal bipyramidal geometry, in
which two Cl atoms occupy axi... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9830Why is nitric oxide paramagnetic in
gaseous state but the solid obtained on cooling it is diamagnetic? Answer: In gaseous state, NO2 exists
as a monomer which has one unpaired electron but in solid state, it dimerises
to N2O4 so no unpaired ... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9831Give one reason to explain why exists butdoes not exist? Answer: Existence of and can be explained on
the basis of size of central atom. Because fluorine is electronegative as
compared to chl... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9832Out of and, which one has higher
bond angle and why? Answer: Bond angle of (H – O – H =
104.5̊) is larger than that of read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9833is known but is not. Why? Answer: Fluorine atom is smaller in size so, six
F- ions can surround a Sulphur atom. The case is not so with
chlorine atom due to its large size. So, read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9834In the ring test of ion, ion reduces nitrate ion
to nitric oxide, which combines with (aq) ion to form brown
complex. Write the reactions involved in the formation of brown ring. Answer: read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9835Explain why ozone is thermodynamically
less stable than oxygen? Answer: Ozone is thermodynamically less stable
than oxygen because its decomposition into oxygen results in the liberation
of heat (is negative) and an
increase in entropy (i... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9836Name three oxoacids of nitrogen. Write
the disproportionation reaction of that oxoacid of nitrogen in which nitrogen
is in + 3 oxidation state. Answer: Three oxoacids of nitrogen having
oxidation state +3 are
(a) HNO2 , nitrous acid
(... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9837PCl5 reacts with finely
divided silver on heating and a white silver salt is obtained, which
dissolves on adding excess aqueous NH3 solution. Write the
reactions involved to explain what happens. Answer: PCl5 reacts with finely
divided si... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9838Match the species given in Column I with
the shape given in Column II and mark the correct option.
read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9839Match the items in Column I and Column II
and mark the correct option.
Column I... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9840In the
following question, a statement of assertion is followed by a statement of
reason.
Assertion (A)
HNO3 makes iron passive.
Reason (R) HNO3
forms a protective layer of ferric nitrate on the surface of iron.
... read moreNEET - Grade 12 - Chemistry - The p-Block Elements - Study ref# 9841In the
following question, a statement of assertion is followed by a statement of
reason.
Assertion (A)
SF6 cannot be hydrolysed but SF4 can be.
Reason (R) Six
F-atoms in SF6 prevent the attack of H2O on Sulphur... read more
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