1 Solid State
Ferrous oxide has a cubic structure with an edge length of the unit cell equal to 5.0 Å. Assuming the density of ferrous oxide to be 3.84 g cm−3, the number of Fe2+ and O2− ions present in each unit cell will be respectively, (use NA=6×1023) 1) 4 and 4 2) 2 and 2 3) 1 and 1 4) 3 and 4
The expression for density $$(d)$$ is as follows: $$d=\dfrac{nM}{VN_A} \implies n=\dfrac{dVN_A}{M} =\dfrac{ 3.84\times (5\times 10^{-8})^3\times 6.023\times 10^{23}}{72} = 4$$
2 Chemistry in Everyday Life
Commonly used antiseptic 'Dettol' is a mixture of
1) o-chlorophenoxylenol + terpineol
2) o-cresol + terpineol
3) phenol + terpineol
4) chloroxylenol + terpineol
One of the most known antiseptics, Dettol is a mixture of terpineol and chloroxylenol. These ingredients make dettol an effective antiseptic-disinfectant that kills bacteria.
3 Alcohols Phenols and Ethers
Phenol reacts with CH3I in presence of NaOH to form methoxybenzene.
Phenoxide is better nucleophile than phenol.
1) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion 2) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion 3) Assertion is correct but Reason is incorrect 4) Both Assertion and Reason are incorrect
Hence both Assertion and Reason are correct and Reason is the correct explanation for Assertion
4 Solid State
The pyknometric density of sodium chloride crystal is 2.165×103 kg m−3 while its X−ray density is 2.178×103 kg m−3. The fraction of unoccupied sites in sodium chloride crystal is: 1) 5.96 2) 5.96×10−2 3) 5.96×10−1 4) 5.96×10−3
First density = $$2.165\times 10^{3}$$
Difference of density $$=( 2178-2165)\ Kg/m^3=13$$ $$Kg/m^{3}$$
Therefore,
5 Thermodynamics
The heat exchange at constant volume for the decomposition of Silver (I) Oxide is found to be 3.66 kJ. The heat change at constant pressure will be
1) > 30.66 kJ
2) < 30.66 kJ
3) 30.66 kJ
4) unpredictable
Solution
Heat change at constant volume for the decomposition of silver(I) oxide = 30.66 kJ.
Ag2O(s)?2Ag(s)+12O2(g)
Here, Δng=+ve
Thus, ΔH>ΔE
Since, ΔE=30.66kJ, ΔH>30.66kJ.
6 Basic Principles of Organic Chemistry
Hexane and 3-methylpentane are examples of:
1) enantiomers
2) stereoisomers
3) diastereomers
4) none of these
SOLUTION
Both hexane and 3-methylpentane have formula of C6H14, Compounds having same molecular formula but different structures due to the different arrangement of atoms or group of atoms in the parental chain are called chain isomers. Hexane and 3-methylpentane are chain isomers.
7 Chemical Bonding and Molecular Structure
According to MO theory which of the list ranks the oxygen species in terms of increasing bond order $$O_2^{2 - },\,O_2^ + ,O_2^ - \,,\,O_2^{2 - }$$ 1) $$O_2^{2 - },\,O_2^ - ,O_2^ + \,,\,{O_2}$$ 2) $$O_2^ + ,\,{O_2},O_2^ - \,,\,O_2^{2 - }$$ 3) $${O_2},\,{O_2},O_2^ + \,,\,O_2^{2 - }$$ 4) $$O_2^{2 - },\,O_2^ - ,{O_2}\,,\,O_2^ + $$
According to MOT bond order is given by the formula:
where NA?, NB? are the number of electrons in antibonding and bonding
Bond order of the following is:
$$O_2^{2 - },\,O_2^ - ,{O_2}\,,\,O_2^ + $$
8 Aldehydes Ketones and Carboxylic Acids
Which one of the following on oxidation with alkaline permangante solution yields benzoic acid ? :
1) Isopropyl chloride 2) Benzyl chloride 3) Chlorobenzene 4) Phenol.
9 Surface Chemistry
KClO3 on heating decomposes into KCl and O2. If some MnO2 is added, the reaction goes much faster because :
1) MnO2 decomposes to give oxygen 2) MnO2 acts as a catalyst 3) better contact is provided by MnO2 4) MnO2 provides heat by reacting
The reaction is as follows: 2KClO3−---heat → 2KCl + 3O2 In this reaction, if MnO2 is used, then the reaction become faster due to catalytic activities of MnO2
(Catalyst is a substance which lowers activation energy of reaction because it provides alternate pathway for reaction. Also, it increases the rate of backward and forward reaction with same extent. Due to this lower activation energy, equilibrium is attained faster but it doesnot change the overall enthalpy of the reaction.)
10 Coordination Compounds
Set of d-orbitals which is used by central metal during formation of MnO4−
1) $$d_{x^2-y^2}, d_{z^2}, d_{xy}$$ 2) $$d_{xy}, d_{yz}, d_{xz}$$ 3) $$d_{x^2-y^2}, d_{xy}, d_{xz}$$ 4) $$d_{x^2-y^2}, d_{z^2}, d_{xz}$$
Set of d-orbitals which is used by central metal during formation of $$MnO_4^-$$ is $$d_{xy}, d_{yz}, d_{xz}$$. In spherical field of four oxide ligands, the five d orbitals are degenerate. They split into $$t_{2g} and e_g$$ levels in tetrahedral field. The three $$t_{2g}$$ orbitals mix with 4s orbital to form $$d^3s$$ hybrid orbitals.
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where NA?, NB? are the number of electrons in antibonding and bonding 