Chemistry 12 past paper 2022

Which of the following carbides is decomposed by water to form $CH_4$ gas?

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Why thermal stability of carbonates of Group-II elements increases down the group? Describe by giving examples.

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Predict the products of reaction between $Na_2O_2$ and ice-cold water:

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Justify why $AlCl_3$ is non-conductor in both solid and molten states (under high pressure) whereas $NaCl$ is conductor in molten state.

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$CO_2$ is gas whereas $SiO_2$ is solid. Explain with the help of their structures.

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Explain the regular and anomalous trends in ionization energies of elements of the 3rd period.

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Identify the elements which show anomalous trend in ionization energy across the third period of periodic table:

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Give reasons for: a. BeO is amphoteric b. BeO is covalent in nature but has high melting point.

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Which of the following will form yellow coloured complex compound?

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Write down the reactions of $[Fe(H_2O)_6]^{3+}$ with $NH_3$, $CO_3^{2-}$ and $SCN^{-}$.

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Which of the following compounds is used as NMR reference?

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a. Why is PbCl₄ thermally unstable whereas PbCl₂ is stable? b. Why does CCl₄ not undergo hydrolysis?

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What is geometrical isomerism? Write down its conditions. Explain with reference to Alkenes and Cycloalkanes giving one example for each.

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Geometry of $[Pt(NH_3)_4]^{2+}$ is square planar. Hybridization of $Pt$ in the complex ion is:

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Why do transition elements show variable oxidation states?

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Write down the chemical reactions to show the oxidation of $[Cr(H_2O)_6]^{3+}$ to $CrO_4^{2-}$ in three steps.

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What is meant by inhibition of enzymes? Explain giving its types.

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In destructive distillation, **Coal** is heated at $500-1000^{\circ}C$ in the absence of air. It gives:

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What is **homologous series**? Draw structures of first four members of homologous series of **acid amides**.

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Describe how $Fe^{2+}$ acts as a catalyst in reaction between peroxodisulphate ion ($S_2O_8^{2-}$) and iodide ion ($I^-$).

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What is iodoform test? Give its any three applications.

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How can **1-Butyne** be prepared from: a. A vicinal dihalide b. A geminal dihalide

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Predict the type of isomerism shown by the following compounds: $CH_3-CH_2-OH$ and $CH_3-O-CH_3$.

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Why is the concept of functional group important in organic chemistry?

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What is Ozone hole? Describe three reasons for its formation. How ozone layer can be protected?

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Which of the following is a **meta-directing group** in electrophilic aromatic substitution reactions of monosubstituted benzene?

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Why the salts of $Be^{2+}$ cannot have more than four water molecules of crystallization?

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Which of the following is more basic?

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Differentiate between structural and stereo isomerism.

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Which of the following base will favour substitution reaction as compared to the elimination reaction?

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Differentiate between **Propyne** and **Propene** by giving two chemical tests.

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Give chemical reactions to predict the products of reaction between 1-Butene and: a. $Br_2 / CCl_4$ b. $Cl_2 + H_2O$ c. $C_6H_5-C(=O)-O-O-H$ (Peroxybenzoic acid)

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Write down the mechanism of $E_1$ reaction and support it by giving one evidence.

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Identify the reactant $X$ in the following conversion: $CH_3-CO-NH_2 + X \rightarrow CH_3-NH_2$

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What is the trend of halide ions as reducing agents? Justify your answer.

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Which of the following alcohols on reaction with $K_2Cr_2O_7/H_2SO_4$ will give an **alkene**?

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Write down the reactions of $CH_3MgCl$ with: a. $CH_3CHO$ b. Formaldehyde ($HCHO$)

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Which of the following alcohols is most reactive in a reaction involving the cleavage of C-O bond?

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What are diazonium salts? How can this salt be prepared from Aniline? What happens when this salt is heated above 10°C?

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Oxidative cleavage of ethane-1,2-diol (glycol) with $HIO_4$ gives:

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Compare **basicity** of following compounds by giving reasons: a. $CH_3-CH_2-NH_2$ b. $NH_3$ c. $CH_3-NH_2$

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Identify the correct order of acidic strength of carboxylic acids, phenols and alcohols.

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Write down the mechanism for dehydration of excess of Ethanol with conc. H₂SO₄ at 140°C.

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Which of the following tests is applied to differentiate between **Ethanal** and **Propanal**?

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Why is phenol more acidic than alcohols?

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Describe the Kolbe-Schmitt reaction of phenol.

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Acetic acid is reacted with $NH_3$ and the resulting compound is strongly heated. Identify the compound formed.

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How can Primary, Secondary and Tertiary alcohols be differentiated by Lucas test?

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Which of the following organic compounds will undergo **Cannizzaro's reaction**?

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Write down two tests to differentiate between Aldehydes and Ketones.

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Which of the following nitrogenous bases is **NOT** present in DNA?

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Write down the reactions of **Acetaldehyde** with: a. Zn/Hg-HCl b. 2,4-DNPH c. C₂H₅OH

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Sucrose is the disaccharide of:

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Write down the reactions for following conversions: a. Acetamide into Ethyl amine b. Acetyl chloride into acetic anhydride c. Calcium acetate into acetone

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Nylon-6,6 is the polymer of:

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Write down the reactions of **Acetic anhydride** with: a. $H_2O$ b. $C_2H_5OH$ c. $NH_3$

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Nail polish remover is the mixture of:

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How can $CH_3COOH$ be prepared from: a. A Grignard reagent b. A Nitrile c. An Alcohol

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Identify **greenhouse gases**:

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How can $CH_3COOH$ be converted into: a. $CH_3CH_2OH$ b. $CH_3CONH_2$

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Which of the following parameters indicates the concentration of oxidizable material in water?

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Write down three differences between DNA and RNA.

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In IR spectrum, a strong peak at $1720 \text{ cm}^{-1}$ indicates the presence of:

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Co-ordination number of Cobalt in $[Co(en)_2Cl_2]Cl$ is:

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How can petrochemical raw materials be classified?

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What is meant by refining of petroleum? State its basic principle.

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What type of electronic transition takes place when an organic compound is subjected to visible radiation in the wavelength range of $200-800 \text{ nm}$?

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Differentiate between Atomic emission spectroscopy and Atomic absorption spectroscopy.

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