Read the passage given below and answer the following questions:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since d electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given.
Choose the correct answer out of the following choices on the basis of the above
passage.
A. Assertion and reason both are correct statements and reason is correct explanation for assertion.
B. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
C. Assertion is correct statement but reason is wrong statement.
D. Assertion is wrong statement but reason is correct statement.
1) Assertion: Cations of transition elements occur in various valence states
Reason: Large number of oxides of transition elements are possible.
2) Assertion: Crystal structure of oxides of transition metals often show defects.
Reason: Ligand field effect cause distortions in crystal structures.
3) Assertion : Transition metals form protective oxide films.
Reason: Oxides of transition metals are always stoichiometric.
4) Assertion: CrO crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by chromium ions.
Reason: Transition metal oxide may be hexagonal close-packed lattice of oxide ions with metal ions filling the octahedral voids.
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since d electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given.
Choose the correct answer out of the following choices on the basis of the above
passage.
A. Assertion and reason both are correct statements and reason is correct explanation for assertion.
B. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
C. Assertion is correct statement but reason is wrong statement.
D. Assertion is wrong statement but reason is correct statement.
1) Assertion: Cations of transition elements occur in various valence states
Reason: Large number of oxides of transition elements are possible.
2) Assertion: Crystal structure of oxides of transition metals often show defects.
Reason: Ligand field effect cause distortions in crystal structures.
3) Assertion : Transition metals form protective oxide films.
Reason: Oxides of transition metals are always stoichiometric.
4) Assertion: CrO crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by chromium ions.
Reason: Transition metal oxide may be hexagonal close-packed lattice of oxide ions with metal ions filling the octahedral voids.
1) (B) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
2) (A) Assertion and reason both are correct statements and reason is correct explanation for assertion.
3) (C) Assertion is correct statement but reason is wrong statement.
4) (D) Assertion is wrong statement but reason is correct statement.
2) (A) Assertion and reason both are correct statements and reason is correct explanation for assertion.
3) (C) Assertion is correct statement but reason is wrong statement.
4) (D) Assertion is wrong statement but reason is correct statement.
Read the passage given below and answer the following questions:
In an ideal crystal, there must be regular repeating arrangement of the constituting particles and its entropy must be zero at absolute zero temperature. However, it is impossible to obtain an ideal crystal and it suffers from certain defects called imperfections. In pure crystal, these defects arises either due to disorder or dislocation of the constituting particles from the normal positions or due to the movement of the particles even at absolute zero temperature. Such defects increase with rise in temperature. In addition to these certain defects arise due to the presence of some impurities. Such defects not only modify the existing properties of the crystalline solids but also impart certain new characteristics to them.
Answer the following MCQs by choosing the most appropriate options:
1) AgCl is crystallized from molten AgCl containing a little \(CdCl_2\). The solid obtained will have
(a) cationic vacancies equal to number of \(Cd^{2+}\) ions incorporated.
(b) cationic vacancies equal to double the number of \(Cd^{2+}\) ions.
(c) anionic vacancies.
(d) neither cationic nor anionic vacancies.
2) Lattice defect per \(10^{15}\) NaCl is 1. What is the number of lattice defects in a mole of NaCl?
(a) 6.02 × \(10^{23}\)
(b) 6.02 × \(10^8\)
(c) \(10^{14}\)
(d) None of these
3) The ionic substances in which the cation and anion are of almost similar size shows
(a) non-stoichiometric defect
(b) Schottky defect
(c) Frenkel defect
(d) all of these
4) Which of the following gives both Frenkel and Schottky defect?
(a) AgCl
(b) CsCl
(c) KCl
(d) AgBr
Read the passage given below and answer the following questions:
All real structures are three-dimensional structures. They can be obtained by stacking two dimensional layers one above the other while placing the second square close packed layer above the first we follow the same rule that was followed when one row was placed adjacent to the other. The second layer is placed over the first layer such that the spheres of the upper layer are exactly above there of the first layer. In his arrangement spheres of both the layers are perfectly aligned horizontally as well as vertically. A metallic element crystallise into a lattice having a ABC ABC pattern and packing of spheres
leaves out voids in the lattice.
1) What type of structure is formed by this arrangement?
(A) ccp
(B) hcp
(C) ccp/fcc
(D) none of the above
2) Name the non-stoichiometric point defect responsible for colour in alkali metal halides.
(A) Frenkel defect
(B) Interstitial defect
(C) Schottky defect
(D) F-centres
3) What is the total volume of atoms in a face centred cubic unit cell of a metal? (r is atomic radius).
(A) 16/3 \(πr^3\)
(B) \(πr^3\)
(C) 24/3 \(πr^3\)
(D) 12/3 \(πr^3\)
4) Which of the following statements not true for the amorphous and crystalline solids?
(A) Amorphous solids are isotropic and crystalline solids are anisotropic.
(B) Amorphous solids are short range order and crystalline solids are long range order.
(C) Amorphous solids melt at characteristic temperature while crystalline solids melt over a range of temperature.
(D) Amorphous solids have irregular shape and crystalline solids have a geometrical shape.
Study the diagram given below and answer the following questions: [Assertion-Reason Type Questions]
[A] – Assertion & reason both statements are correct and reason is the correct explanation of assertion.
[B] – Assertion & reason both are the correct statements but reason is not the correct explanation of the assertion.
[C] – Assertion is correct statement and reason is incorrect statement.
[D] – Assertion is incorrect statement and reason is correct statement
1) Assertion (A): The diagram shows Schottky defect.
Reason (R): Schottky defect occurs in ionic solids.
2) Assertion (A): LiCl Crystal is pink.
Reason (R): Pink colour of LiCl crystal is due to excess Lithium.
3) Assertion (A): The crystal lattice density increases due to the
defect shown in the diagram.
Reason (R): Tetrahedral voids are surrounded by 4 constituent
particles.
4) Assertion (A): AgCl shows Frenkel defect while NaCl does not.
Reason (R): Frenkel defect is shown when anionic vacancies are
occupied by unpaired electrons.
Assertion: Na⁺ and Al³⁺ are isoelectronic but the magnitude of ionic radius of Al³⁺ is less than that of Na⁺
Reason: The magnitude of an effective nuclear charge on the outer shell electrons in Al³⁺ is greater than that of Na⁺.
[A] – Assertion & reason both statements are correct and reason is the correct explanation of assertion.
[B] – Assertion & reason both are the correct statements but reason is not the correct explanation of the assertion.
[C] – Assertion is correct statement and reason is incorrect statement.
[D] – Assertion is incorrect statement and reason is correct statement
Assertion (A): Crystalline solids are anisotropic in nature.
Reason (R): Some of their physical properties show same electrical and optical properties in different directions in the same crystal.
[A] – Assertion & reason both statements are correct and reason is the correct explanation of assertion.
[B] – Assertion & reason both are the correct statements but reason is not the correct explanation of the assertion.
[C] – Assertion is correct statement and reason is incorrect statement.
[D] – Assertion is incorrect statement and reason is correct statement
Assertion: White ZnO becomes yellow upon heating.
Reason: On heating ZnO loses oxygen and free electrons go into exited stated and upon returning imparts yellow radiation.
[A] – Assertion & reason both statements are correct and reason is the correct explanation of assertion.
[B] – Assertion & reason both are the correct statements but reason is not the correct explanation of the assertion.
[C] – Assertion is correct statement and reason is incorrect statement.
[D] – Assertion is incorrect statement and reason is correct statement
Assertion: In caesium chloride crystal, Cs⁺ is present on the centre of cube of the unit cell.
Reason: For N⁻ atoms adopting fcc arrangement, there are 2N tetrahedral voids.
[A] – Assertion & reason both statements are correct and reason is the correct explanation of assertion.
[B] – Assertion & reason both are the correct statements but reason is not the correct explanation of the assertion.
[C] – Assertion is correct statement and reason is incorrect statement.
[D] – Assertion is incorrect statement and reason is correct statement
Read the passage given below and answer the following questions:
In an ideal crystal, there must be regular repeating arrangement of the constituting particles and its entropy must be zero at absolute zero temperature. However, it is impossible to obtain an ideal crystal and it suffers from certain defects called imperfections. In pure crystal, these defects arises either due to disorder or dislocation of the constituting particles from the normal positions or due to the movement of the particles even at absolute zero temperature. Such defects increase with rise in temperature. In addition to these certain defects arise due to the presence of some impurities. Such defects not only modify the existing properties of the crystalline solids but also impart certain new characteristics to them.
Answer the following MCQs by choosing the most appropriate options:
1) AgCl is crystallized from molten AgCl containing a little \(CdCl_2\). The solid obtained will have
(a) cationic vacancies equal to number of \(Cd^{2+}\) ions incorporated.
(b) cationic vacancies equal to double the number of \(Cd^{2+}\) ions.
(c) anionic vacancies.
(d) neither cationic nor anionic vacancies.
2) Lattice defect per \(10^{15}\) NaCl is 1. What is the number of lattice defects in a mole of NaCl?
(a) 6.02 × \(10^{23}\)
(b) 6.02 × \(10^8\)
(c) \(10^{14}\)
(d) None of these
3) The ionic substances in which the cation and anion are of almost similar size shows
(a) non-stoichiometric defect
(b) Schottky defect
(c) Frenkel defect
(d) all of these
4) Which of the following gives both Frenkel and Schottky defect?
(a) AgCl
(b) CsCl
(c) KCl
(d) AgBr
The sequence of bases along the DNA and RNA chain establishes its primary structure which controls the specific properties of the nucleic acid. An RNA molecule is usually a single chain of ribose-containing nucleotide. On the basis of X-ray analysis of DNA, J.D., Watson and F.H.C. CYST (shared noble prize in 1962) proposed a three dimensional secondary structure for DNA. DNA molecule is a long and highly complex, spirally twisted, double helix, ladder like structure. The two polynucleotide chains or strands are linked up by hydrogen bonding between the nitrogenous base molecules of their nucleotide monomers. Adenine (purine) always links with thymine (pyrimidine) with the help of two hydrogen bonds and guanine (purine) with cytosine (pyrimidine) with the help of three hydrogen bonds. Hence, the two strands extend in opposite directions, i.e., are
antiparallel and complimentary.
In these questions (Q. No. i-iv), a statement of assertion followed by a statement of reason is given.
Choose the correct answer out of the following choices.
a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
b) Assertion and reason both are correct statements but reason is not correct explanation for assertion. c) Assertion is correct statement but reason is wrong statement
d) Assertion is wrong statement but reason is correct statement.
i) Assertion - DNA molecules and RNA molecules are found in the nucleus of a cell.
Reason : There are two types of nitrogenous bases, purines and pyrimidines. Adenine (A) and guanine (G)are substituted purines; cytokine (C), thymine (T) arid uracil (U) are substituted pyrimidines.
ii) Assertion .- In both DNA and RNA, heterocyclic base and phosphate ester linkages are at C- 1’ and C-5’respectively of the sugar molecule.
Reason : Nucleotides and nucleosides mainly differ from each other in presence of phosphate units.
iii)Assertion .- The backbone of RNA molecule is a linear chain consisting of an alternating units of heterocylic base, D-ribose and a phosphate.
Reason : The segment of RNA which acts as the instruction manual for the synthesis of protein is ribose.
iv) Assertion.- In DNA, the complementary bases are, adenine and guanine; thymine and cytosine.
Reason : The phenomenon of mutation is chemical change in DNA molecule.
An organic compound A having molecular formula \(C_6\)\(H_6\)O turn blue litmus solution into red but does not react with sodium bicarbonate, but when treated with bromine water then form a white ppt of compound B. when compound A react with chloroform in presence of aqueous caustic soda solution at 340K then form two compound C and D. When compound A treated with caustic soda then form compound E compound E when treated with methyl halide then form compound F.
Read the above passage carefully and answer the following questions:
(i) The name of compound is:
(a) 2-methyl propene-2-ol
(b) 2-methyl phenol
(c) 2,4,6-tribromophenol
(d) Butane 1-ol
(ii) Which are isomers of each other
(a) A and C
(b) B and C
(c) C and D
(d) D and E
(iii) The IUPAC name of compound F is
(a) Anisole
(b) Methoxybenzene
(c) Salicylaldehyde
(d) 2-methyl propene-2-ol
(iv) When compound E treated with ethyl iodide then ...... form.
(a) Ehoxybenzene
(b) Ethoxy hexane
(c) Propoxypropane
(d) Benzaldehyde
(v) On oxidation with sodium dichromate and conc \(H_2\)\(SO_4\) phenol gives
(a) Benzaldehyde
(b) p-Benzoquinone
(c) o-Benzoquinone
(d) m-benzoquinone
Boiling point or freezing point of liquid solution would be affected by the dissolved solids in the liquid phase. A soluble solid in solution has the effect of raising its boiling point and depressing its freezing point. The addition of non-volatile substances to a solvent decreases the vapor pressure and the added solute particles affect the formation of pure solvent crystals. According to many researches the decrease in freezing point directly correlated to the concentration of solutes dissolved in the solvent. This phenomenon is expressed as freezing point depression and it is useful for several applications such as freeze concentration of liquid food and to find the molar mass of an unknown solute in the solution. Freeze concentration is a high quality liquid food concentration method where water is removed by forming ice crystals. This is done by cooling the liquid food below the freezing point of the solution. The freezing point depression is referred as a colligative property and it is proportional to the molar concentration of the solution (m), along with vapor pressure lowering, boiling point elevation, and osmotic pressure. These are physical characteristics of solutions that depend only on the identity of the solvent and the concentration of the solute. The characters are not depending on the solute’s identity.
Answer the following MCQs by choosing the most appropriate options:
(i) When a non volatile solid is added to pure water it will-
(a) boil above \(100^\circ\)C and freeze above \(0^\circ\)C.
(b) b) boil below \(100^\circ\)C and freeze above \(0^\circ\)C.
(c) boil above \(100^\circ\)C and freeze below \(0^\circ\)C.
(d) boil below \(100^\circ\)C and freeze below \(0^\circ\)C.
(ii) Colligative properties are
(a) dependent only on the concentration of the solute and independent of the solvent’s and solute’s
identity.
(b) dependent only on the identity of the solute and the concentration of the solute and independent
of the solvent’s identity.
(c) dependent on the identity of the solvent and solute and thus on the concentration of the solute.
(d) dependent only on the identity of the solvent and the concentration of the solute and independent
of the solute’s identity.
(iii) Assume three samples of juices A, B and C have glucose as the only sugar present in them. The concentration of sample A, B and C are 0.1 M, 0.5 M and 0.2 M respectively. Freezing point will be highest for the fruit juice
(a) A
(b) B
(c) C
(d) all have same freezing point
(iv) Identify which of the following is a colligative property?
(a) Freezing point
(b) Boiling point
(c) Osmotic pressure
(d) All of the above
Molecular Nitrogen \(N_2\) comprises about 78% by volume of Earth’s atmosphere. It occurs as Sodium nitrate, \(NaNO_3\)(chile saltpeter) & Potassium nitrate, \(KNO_3\)(Indian altpeter) in earth’s crust. Since nitrate are very soluble in water so these are not wide spread in the earth’s crust. Nitrogen is also an important constituent of amino acids, protein & nucleic acids in plants & animals.
Nitrogen shows anomalous behavior from rest of the elements due to following reasons;
Smaller size, high ionization enthalpy, high electronegativity & absence of d-orbital. It has unique ability to form p∏-p∏ multiple bonds with itself & with small size atoms like C & O as they have small size & high electronegativity. Heavier elements of this group do not form p∏-p∏ bonds as their atomic orbitals are so large & diffuse that they can’t have effective overlapping.
Thus Nitrogen exists as diatomic molecules \(N_2\) with a triple bond. Consequently, its bond enthalpy (941.4 KJ \(mol^{-1}\)) is very high. P, As & Sb form only single bonds as P-P, As-As & Sb-Sb. Due to much bond enthalpy N is much less reactive than P.
Single N-N bond is weaker than single P-P bond due to high interelectronic repulsion of the non bonding electrons, owing to small bond length. As a result, the catenation tendency is weaker in nitrogen. Hence nitrogen exists as gas while phosphorus exists as solid.
Nitrogen can’t form d∏- d∏ bond due to absence of d- orbitals so it can’t expand its covalency beyond four as heavier members can.
The following questions are multiple choice questions. choose the most appropriate answer.
1) Among group 15 elements which exists as gas at room temperature
a) Arsenic
b) Bismuth
c) Nitrogen
d) Phosphorous
2) The stability of +5 oxidation state decreases and that of +3 state increases down the group in group 15 elements due to
a) inert pair effect
b) decrease in ionisation enthalpy
c) increase in size
d) shielding effect
3) Nitrogen is restricted to a maximum covalency of 4 because of
a) absence of d-orbitals
b) presence of d-orbitals
c) absence of s and p-orbitals
d) none of the above
4) Extra pure \(N_2\) can be obtained by heating
a) \(NH_3\) with CuO
b) \(NH_4NO_3\)
c) \(\left(NH_4\right)_2Cr_2O_7\)
d) \(Ba\left(N_3\right)_2\)
5) Catenation tendency is weaker in nitrogen, because of
a) single N–N bond is weaker
b) single N–N bond is stronger
c) ability to form pi bonds by N atoms
d) none of the above
Read the passage given below and answer the following questions:
All real structures are three-dimensional structures. They can be obtained by stacking two dimensional layers one above the other while placing the second square close packed layer above the first we follow the same rule that was followed when one row was placed adjacent to the other. The second layer is placed over the first layer such that the spheres of the upper layer are exactly above there of the first layer. In his arrangement spheres of both the layers are perfectly aligned horizontally as well as vertically. A metallic element crystallise into a lattice having a ABC ABC pattern and packing of spheres
leaves out voids in the lattice.
1) What type of structure is formed by this arrangement?
(A) ccp
(B) hcp
(C) ccp/fcc
(D) none of the above
2) Name the non-stoichiometric point defect responsible for colour in alkali metal halides.
(A) Frenkel defect
(B) Interstitial defect
(C) Schottky defect
(D) F-centres
3) What is the total volume of atoms in a face centred cubic unit cell of a metal? (r is atomic radius).
(A) 16/3 \(πr^3\)
(B) \(πr^3\)
(C) 24/3 \(πr^3\)
(D) 12/3 \(πr^3\)
4) Which of the following statements not true for the amorphous and crystalline solids?
(A) Amorphous solids are isotropic and crystalline solids are anisotropic.
(B) Amorphous solids are short range order and crystalline solids are long range order.
(C) Amorphous solids melt at characteristic temperature while crystalline solids melt over a range of temperature.
(D) Amorphous solids have irregular shape and crystalline solids have a geometrical shape.
Read the passage given below and answer the following questions:
Nucleophilic substitution reactions are of two types; substitution nucleophilic bimolecular (SN2) and substitution nucleophilic unimolecular (SN1) depending on molecules taking part in determining the rate of reaction. Reactivity of alkyl halide towards SN1 and SN2 reactions depends on various factors such as steric hindrance, stability of intermediate or transition state and polarity of solvent. SN2 reaction mechanism is favoured mostly by primary alkyl halide or transition state and polarity of solvent, SN2 reaction mechanism is favoured mostly by primary alkyl halide then secondary and then tertiary. This order is reversed in case of SN1 reactions.
(i) Which of the following is most reactive towards nucleophilic substitution reaction?
(a) \(C_6\)\(H_5\)Cl
(b) \(CH_2\)=CHCl
(c) \(ClCH_2\)\(CH=CH_2\)
(d) \(CH_3\)CH=CHCl
(ii) Isopropyl chloride undergoes hydrolysis by
(a) SN1 mechanism
(b) SN2 mechanism
(c) SN1 and SN2 mechanism
(d) neither SN1 nor SN2 mechanism
(iii) Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because of
(a) insolubility
(b) instability
(c) inductive effect
(d) steric hindrance
(iv) Which of the following is the correct order of decreasing SN2 reactivity?
(a) \(RCH_2\)X > \(R_2\)CHX > \(R_3\)CX
(b) \(R_3\)CX > \(R_2\)CHX > \(RCH_2\)X
(c) \(R_2\)CHX > \(R_3\)CX > \(RCH_2\)X
(d) \(RCH_2\)X > \(R_3\)CX > \(R_2\)CHX
(v) An organic molecule necessarily shows optical activity if it-
a) contains asymmetric carbon atoms
b) is non-polar
c) is non-superimposable on its mirror image
d) is superimposable on its mirror image