Question
Explain the structure of nucleic acid compounds.
✓
Answer
→"A unit formed by the attachment of a base to 1' position of sugar is known as nucleoside."
→In nucleosides the sugar carbons are numberd as 1', 2', 3' etc. In order to distinguish these from the bases - when nucleoside is linked to phosphoric acid at 5'-position of sugar moiety, we got a nucleotide.
→Nucleotides are joined together by phosphodiester linkage between 5' and 3' carbon atoms of the pentose sugar. The formation of a typical dinucleotide is shown in figure.
A simplified version of nucleic acid chain is as shown below.
→In nucleosides the sugar carbons are numberd as 1', 2', 3' etc. In order to distinguish these from the bases - when nucleoside is linked to phosphoric acid at 5'-position of sugar moiety, we got a nucleotide.
→Nucleotides are joined together by phosphodiester linkage between 5' and 3' carbon atoms of the pentose sugar. The formation of a typical dinucleotide is shown in figure.
A simplified version of nucleic acid chain is as shown below.
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Read the passage given below and answer the following questions:
Glucose is known as dextrose because it occurs in nature as the optically active dextrorotatory isomer. lt is essential constituent of human blood. The blood normally contains $65$ to $110mg$ of glucose per 100mL (hence named Blood sugar). The level may be much higher in diabetic persons. The urine of diabetic persons also contain considerable amount of glucose. ln combined form, it occurs in cane sugar and polysaccharides such as starch and cellulose.
Glucose has an aldehyde group $(-CHO)$, one primary alcoholic group $(-CH_2OH)$ and four secondary alcoholic groups $(-CHOH)$ in their structure. Due to the presence five hydroxyl groups $(-OH)$. glucose undergoes acetylation. Glucose also undergoes oxidation with mild oxidising agents like bromine water as well as with strong oxidising agents like nitric acid. Since glucose is readily oxidised, it acts as a strong reducing agent and reduces Tollen's reagent and Fehling solution. Glucose exists in two crystalline forms: $\alpha$-D-glucose and $\beta$-D-glucose. If either of the two forms is dissolved in water and allowed to stand, the specific rotation of the solution changes gradually, until a constant value is obtained. This change is called mutarotation.
A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
→Glucose is known as dextrose because it occurs in nature as the optically active dextrorotatory isomer. lt is essential constituent of human blood. The blood normally contains $65$ to $110mg$ of glucose per 100mL (hence named Blood sugar). The level may be much higher in diabetic persons. The urine of diabetic persons also contain considerable amount of glucose. ln combined form, it occurs in cane sugar and polysaccharides such as starch and cellulose.
Glucose has an aldehyde group $(-CHO)$, one primary alcoholic group $(-CH_2OH)$ and four secondary alcoholic groups $(-CHOH)$ in their structure. Due to the presence five hydroxyl groups $(-OH)$. glucose undergoes acetylation. Glucose also undergoes oxidation with mild oxidising agents like bromine water as well as with strong oxidising agents like nitric acid. Since glucose is readily oxidised, it acts as a strong reducing agent and reduces Tollen's reagent and Fehling solution. Glucose exists in two crystalline forms: $\alpha$-D-glucose and $\beta$-D-glucose. If either of the two forms is dissolved in water and allowed to stand, the specific rotation of the solution changes gradually, until a constant value is obtained. This change is called mutarotation.
A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: A diabetic person carries a packet of glucose with him always.
- Assertion: On oxidation with nitric acid, glucose as well as gluconic acid both yield saccharic acid.
- Assertion: Glucose reacts with acetyl chloride to form pentaacetyl glucose.
- Assertion: A certain compound gives negative test with ninhydrin and positive test with Benedict's solution, the compound is an amino acid.
- Assertion: The rapid interconversion of $\alpha$-D-glucose and $\beta$-D-glucose in solution is known as racemisation.
Read the passage given below and answer the following questions:
The molecular compounds which are formed from the combination of two or more simple stable compounds and retain their identity in the solid as well as in the dissolved state are called coordination compounds. Their properties are completely different from the constituents. ln coordination compounds, the central metal atom or ion is linked to a number ofions or neutral molecules, called ligands, by coordinate bonds. For example, Dimethylglyoxime (dmg) is a bid en date ligand chelating large amounts of metals. When dimethyl glyoxime is added to alcoholic solution of $NiCl_2$ and ammonium hydroxide is slowly added to it, a rosy red precipitate of a complex is formed.
The following questions are multiple choice questions. Choose the most appropriate answer:
- The structure of the complex is:
- Oxidation number of Ni in the given complex is:
- $+3$
- $+1$
- $+2$
- $Zero$
- Hybridisation and structure of the complex is:
- $Sp^3$, tetrahedral.
- $dsp^2$, square planar.
- $Sp^3$, square planar.
- $Sp^3d$, trigonal bipyramidal.
- Which of the following is true about this complex?
- It is paramagnetic, containing $2$ unpaired electrons.
- It is paramagnetic, containing $1$ unpaired electron.
- It is paramagnetic, containing $4$ unpaired electrons.
- It is diamagnetic with no unpaired electron.
- Which one will give test for $Fe^{3+}$ ions in the solution?
- $[Fe(CN)_6]^{3-}$
- $[Fe(CN)_6]^{2-}$
- $(NH_4)_2SO_4·FeSO_4·6H_2O$
- $Fe_2(S0_4)_3$
Read the passage given below and answer the following questions: Aniline activates the benzene ring by increasing electron density at ortho- and para-positions. Hence, it is o-, p-directing. -NH2 group strongly activates the ring therefore it is difficult to stop the reaction at monosubstitution stage. Among electrophilic substitution reaction, direct nitration of aniline is not done to get o- and p-nitroaniline because lone pair of electrons present at nitrogen atom will accept proton from nitrating mixture to give anilinium ion which is meta-directing. Aniline with $NaNO_2$ and HCI forms benzene diazonium chloride at very low temperature. Aromatic amines react with nitrous acid to form a yellow oily liquid known as N-nitrosoamines. A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
→- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: Nitrating mixture used for carrying out nitration of benzene consists of cone. $HNO_3$ + cone. $H_2SO_4$.
- Assertion: Anilinium chloride is more acidic than ammonium chloride.
- Assertion: Nitrobenzene can be prepared from benzene by using mixture of cone. $HNO_3$ and cone. $H_2SO_4$.
- Assertion: In strongly acidic solution, aniline becomes less reactive towards electrophilic reagents.
- Assertion: Nitration of aniline can be done conveniently by protecting $-NH_2$ group through acetylation.
Read the passage given below and answer the following questions:
If some solute is added to a solvent, the boiling point of solution increases. This is known as elevation in baiting point.
$\Delta\text{T}_\text{b}=\text{K}_\text{b}\text{m}$ where, $K_b =$ Molal elevation constant,
$\Delta\text{T}_\text{b}\propto\text{m}$
Hence, it is a colligative property,
Also, $\text{K}_\text{b}=\frac{\text{MRT}^2_\text{b}}{\Delta\text{Vap}\text{H}\times1000}$
where, $M =$ Molar mass of solvent,
$\Delta\text{vap}$ $H = $Enthalpy of vaporisation,
Molar mass can also be calculated using elevation in boiling point.
$\text{M}_\text{B}=\frac{\text{K}_\text{B}\times\text{W}_\text{B}\times1000}{\Delta\text{T}_\text{b}\times\text{W}_\text{A}}$
A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
→If some solute is added to a solvent, the boiling point of solution increases. This is known as elevation in baiting point.
$\Delta\text{T}_\text{b}=\text{K}_\text{b}\text{m}$ where, $K_b =$ Molal elevation constant,
$\Delta\text{T}_\text{b}\propto\text{m}$
Hence, it is a colligative property,
Also, $\text{K}_\text{b}=\frac{\text{MRT}^2_\text{b}}{\Delta\text{Vap}\text{H}\times1000}$
where, $M =$ Molar mass of solvent,
$\Delta\text{vap}$ $H = $Enthalpy of vaporisation,
Molar mass can also be calculated using elevation in boiling point.
$\text{M}_\text{B}=\frac{\text{K}_\text{B}\times\text{W}_\text{B}\times1000}{\Delta\text{T}_\text{b}\times\text{W}_\text{A}}$
A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: In a pressure cooker, the water is brought to boil. The cooker is then removed from the stove. Now on removing the lid of pressure cooker, the water starts boiling again.
- Assertion: On dissolving $3.24g$ of sulphur in $40g$ of benzene, boiling point of solution get higher than that of benzene by $0.081K$, then the formula of sulphur is $S_8. (K_b$ for benzene $= 2.53K\ kg\ mol^{-1})$
- Assertion: When sugar is added to water, boiling point of water increases.
- Assertion: Cooking time in pressure cookers is reduced.
- Assertion: Elevation in boiling point of two isotonic solutions is same.
Read the passage given below and answer the following questions: Lucas test is a test to differentiate between primary, secondary and tertiary alcohols. This test consists of treating an alcohol with Lucas' reagent, and turbidity, due to the formation of insoluble alkyl chloride, is observed. Lucas test is based on the difference in reacting of three classes of alcohols with hydrogen chloride via $S_N1$ reaction. The different reactivity reflects the differing ease of formation of the corresponding carbocations. In these questions $(Q.$ No. $i-iv),$ a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.
→- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: Equimolar mixture of cone. $HCI$ and anhydrous $ZnCl_2$ is called Lucas' reagent.
- Assertion: $2-$Methyl$-2-$butanol gives no turbidity with Lucas' reagent at room temperature.
- Assertion: Tertiary alcohols react fastest with Lucas' reagent by $S_N1$ mechanism.
- Assertion: Amongst the compounds, $H2C = CHCH_2OH (I), C_6H_5OH (II), CH_3CH_2CH_2OH (III)$ and $(CH_3)_3COH (IV),$ only $(IV)$ reacts with Lucas' reagent at room temperature.
- Assertion: Lucas test can be used to distinguish between $1-$propanol and $2-$propanol.
Amines are basic in nature. The $pK_b$ value is a measure of the basic strength of an amine. Lower the value of $pK_b$ more basic is the amine. The effect of substituent on the basic strength of amines in aqueous solution was determined using titrations. The substituent $"X"$ replaced $"-CH_2"$ group in piperidine $($ compound $1)$ and propylamine $CH_3CH_2CH_2NH_2, ($compound $2).$
Compound $1:$
Compound $2: HXCH_2CH_2NH_2$
(source: Hall Jr, $H. K. (1956).$ Field and inductive effects on the base strengths of amines. Journal of the American Chemical Society, $78(11), 2570-2572.) $
Study the above data and answer the following questions:
$a.$ Plot a graph between the electronegativity of the substituent vs $pK_b$ value of the corresponding substituted propyl amine $($ given that $pK_a + pK_b =14).$ Is there any relation between the electronegativity of the substituent and its basic strength?
$b.$ The electronegativity of the substituent $"C6H5CON\ "$ is $3.7,$ what is the expected pKa value of compound $C_6H_5CONHCH_2CH_2NH_2?$
$(i) \ 9.9 \ (ii) \ 9.5 \ (iii) \ 9.3 \ (iv) \ 9.1$
$c.$ The pKa value of the substituted piperidine formed with substituent $"X\ "$ is found to be $8.28.$ What is the expected electronegativity of $"X\ "$
$(i)\ 3.5 \ (ii)\ 3.4 \ (iii)\ 3.8\ (iv) \ 3.1$
→Compound $1:$
Compound $2: HXCH_2CH_2NH_2$
(source: Hall Jr, $H. K. (1956).$ Field and inductive effects on the base strengths of amines. Journal of the American Chemical Society, $78(11), 2570-2572.) $
Study the above data and answer the following questions:
$a.$ Plot a graph between the electronegativity of the substituent vs $pK_b$ value of the corresponding substituted propyl amine $($ given that $pK_a + pK_b =14).$ Is there any relation between the electronegativity of the substituent and its basic strength?
$b.$ The electronegativity of the substituent $"C6H5CON\ "$ is $3.7,$ what is the expected pKa value of compound $C_6H_5CONHCH_2CH_2NH_2?$
$(i) \ 9.9 \ (ii) \ 9.5 \ (iii) \ 9.3 \ (iv) \ 9.1$
$c.$ The pKa value of the substituted piperidine formed with substituent $"X\ "$ is found to be $8.28.$ What is the expected electronegativity of $"X\ "$
$(i)\ 3.5 \ (ii)\ 3.4 \ (iii)\ 3.8\ (iv) \ 3.1$
Read the passage given below and answer the following questions:
Transition elements are elements that have partially filled d-orbitals. The configuration of these elements corresponds to $(n - 1)d^{1-10}ns^{1-2}.$ It is important to note that the elements mercury, cadmium and zinc are not considered transition elements because of their electronic configurations, which corresponds to $(n - 1)d^{10}ns^2.$ Some general properties of transition elements are:
These elements can fonn coloured compounds and ions due to $d-d$ transition;
These elements exhibit many oxidation states;
A large variety of ligands can bind themselves to these elements, due to this, a wide variety of stable complexes formed by these ions. The boiling and melting point of these elements are high. These elements have a large ratio of charge to the radius.
In these questions $(Q. No. i-iv),$ a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.
→Transition elements are elements that have partially filled d-orbitals. The configuration of these elements corresponds to $(n - 1)d^{1-10}ns^{1-2}.$ It is important to note that the elements mercury, cadmium and zinc are not considered transition elements because of their electronic configurations, which corresponds to $(n - 1)d^{10}ns^2.$ Some general properties of transition elements are:
These elements can fonn coloured compounds and ions due to $d-d$ transition;
These elements exhibit many oxidation states;
A large variety of ligands can bind themselves to these elements, due to this, a wide variety of stable complexes formed by these ions. The boiling and melting point of these elements are high. These elements have a large ratio of charge to the radius.
In these questions $(Q. No. i-iv),$ a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: Tungsten has very high melting point.
- Assertion: $Zn, Cd$ and $Hg$ are normally not considered transition metals.
- Assertion: Copper metal gets readily corroded in acidic aqueous solution such as $HCl$ and dil. $H_2SO_4.$
- Assertion: Tailing of mercury occurs on passing ozone through it.
- Assertion: Transition metals are poor reducing agents.
Read the passage given below and answer the following questions:
Proteins are high molecular mass complex biomolecules of amino acids. The important proteins required for our body are enzymes, hormones, antibodies, transport proteins, structural proteins, contractile proteins etc. Except for glycine, all $\alpha$-amino acids have chiral carbon atom and most of them have L-configuration. The amino acids exists as dipolar ion called zwitter ion, in which a proton goes from the carboxyl group to the amino group. A large number of $\alpha$-amino acids are joined by peptide bonds forming polypeptides. The peptides having very large molecular mass (more than 10,000) are called proteins. The structure of proteins is described as primary structure giving sequence of linking of amino acids; secondary structure giving manner in which polypeptide chains are arranged and folded; tertiary structure giving folding, coiling or bonding polypeptide chains producing three dimensional structures and quaternary structure giving arrangement of sub-units in an aggregate protein molecule.
A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
→Proteins are high molecular mass complex biomolecules of amino acids. The important proteins required for our body are enzymes, hormones, antibodies, transport proteins, structural proteins, contractile proteins etc. Except for glycine, all $\alpha$-amino acids have chiral carbon atom and most of them have L-configuration. The amino acids exists as dipolar ion called zwitter ion, in which a proton goes from the carboxyl group to the amino group. A large number of $\alpha$-amino acids are joined by peptide bonds forming polypeptides. The peptides having very large molecular mass (more than 10,000) are called proteins. The structure of proteins is described as primary structure giving sequence of linking of amino acids; secondary structure giving manner in which polypeptide chains are arranged and folded; tertiary structure giving folding, coiling or bonding polypeptide chains producing three dimensional structures and quaternary structure giving arrangement of sub-units in an aggregate protein molecule.
A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: Except glycine, all naturally occurring CL-amino acids are optically active.
- Assertion: All amino acids are optically active.
- Assertion: In $\alpha$-helix structure, intramolecular H-bonding takes place whereas in $\beta$-pleated structure, intermolecular H-bonding takes place.
- Assertion: Secondary structure of protein refers to regular folding patterns of continuos portions of the polypeptide chain.
- Assertion: The helical structure of protein is stabilised by intramolecular hydrogen bond between -NH and carbonyl oxygen.
Read the passage given below and answer the following questions:
Amines are basic in nature. The basic strength of amines can be expressed by their dissociation constant, $K_b$ or $pK_b$.
$\text{RNH}_2+\text{H}_2\text{O}\rightleftharpoons\text{RNH}^+_3+\text{OH}^-$
$\text{k}_\text{b}=\frac{[\text{RNH}^+_3][\text{OH}^-]}{[\text{RNH}_2]}\text{and}\text{ pk}_\text{b}=-\log\text{k}_\text{b}$
Greater the $K_b$ value or smaller the $pK_b$ value, more is the basic strength of a mine. Aryl amines such as aniline are less basic than aliphatic amines due to the involvement of lone pair of electrons on N-atom with the resonance in benzene. In derivatives of aniline, the electron releasing groups increase the basic strength while electron withdrawing groups decrease the basic strength. The base weakening effect of electron withdrawing group and base strengthening effect of electron releasing group is more marked at p-position than at m-position. a-Substituted aniline is less basic than aniline due to ortho effect and is probable due to combination of electronic and steric effect.
The following questions are multiple choice questions. Choose the most appropriate answer:
→Amines are basic in nature. The basic strength of amines can be expressed by their dissociation constant, $K_b$ or $pK_b$.
$\text{RNH}_2+\text{H}_2\text{O}\rightleftharpoons\text{RNH}^+_3+\text{OH}^-$
$\text{k}_\text{b}=\frac{[\text{RNH}^+_3][\text{OH}^-]}{[\text{RNH}_2]}\text{and}\text{ pk}_\text{b}=-\log\text{k}_\text{b}$
Greater the $K_b$ value or smaller the $pK_b$ value, more is the basic strength of a mine. Aryl amines such as aniline are less basic than aliphatic amines due to the involvement of lone pair of electrons on N-atom with the resonance in benzene. In derivatives of aniline, the electron releasing groups increase the basic strength while electron withdrawing groups decrease the basic strength. The base weakening effect of electron withdrawing group and base strengthening effect of electron releasing group is more marked at p-position than at m-position. a-Substituted aniline is less basic than aniline due to ortho effect and is probable due to combination of electronic and steric effect.
The following questions are multiple choice questions. Choose the most appropriate answer:
- Which of the following has lowest $pK_b$ value?
- The strongest base among the following is:
- $C_6H_5NH_2$
- $p-NO_2 - C_6H_4NH_2$
- $m-NO_2 - C_6H_4NH_2$
- $C_6H_5CH_2NH_2$
- Maximum $pK_b$ value of:
- $(CH_3CH_2)_2NH$
- $(CH_3)_2NH$
- The order of basic strength among the following amines in benzene solution is:
- Methylamine is more basic than $NH_3$.
- Amines form hydrogen bonds.
- Ethylamine has higher boiling point than propane.
- Dimethylamine is less basic than methylamine.
- $CH_3CH_2NH_2$ contains a basic $-NH_2$ group, but $CH_3CONH_2$ does not because:
- Acetamide is amphoteric in character.
- In ethylamine the electron pair on N-atom is delocalised by resonance.
- In ethylamine there is no resonance while in acetamide the lone pair of electrons on N-atom is delocalised and is less available for protonation.
- None of these.
The following reaction, $\text{A}_{(\text{g})}\xrightarrow{\ \ \triangle\ \ \ }\text{P}_{(\text{g})}+\text{Q}_{(\text{g})}+\text{R}_{(\text{g})},$ follows first order kinetics. The half-life period of this reaction is $69.3s$ at $500^\circ C$. The gas A is enclosed in a container at $500^\circ C$ and at a pressure of $0.4$ atm.
The following questions are multiple choice questions. Choose the most appropriate answer:
→The following questions are multiple choice questions. Choose the most appropriate answer:
- The rate constant for the reaction is:
- $0.4s^{-1}$
- $0.02s^{-1}$
- $0.01s^{-1}$
- $0.3s^{-1}$
- The pressure of the gas $A$ after $230$ s will be:
- $0.04$ atm
- $0.36$ atm
- $0.4$ atm
- $0.036$ atm
- The total pressure of the system after $230$ swill be:
- $2.15$ atm
- $1.12$ atm
- $0.4$ atm
- $3.08$ atm
- The plot ofln[A] vs twill be:
- Linear with slope $= k$
- Linear with intercept $= In[A]_0$
- Linear with slope $= In[A]_0$
- Linear with intercept $= [A]_0$
- Which of the following is not an example of first order reaction?
- $\text{C}_2\text{H}_{4(\text{g})}+\text{H}_{2(\text{g})}\rightarrow\text{C}_2\text{H}_{6(\text{g})}$
- $2\text{N}_2\text{O}_{5(\text{g})}\rightarrow4\text{NO}_{2(\text{g})}+\text{O}_{2(\text{g})}$
- $2\text{N}\text{H}_{3(\text{g})}\xrightarrow[\triangle]{\text{pt}}\text{N}_{2(\text{g})}+3\text{H}_{2(\text{g})}$
- $2\text{N}_2\text{O}_{(\text{g})}\xrightarrow{\ \ \triangle\ \ }2\text{N}_{2(\text{g})}+\text{O}_{2(\text{g})}$