JKBOSE Chemistry: Solved Previous Year’s Question Paper for NCERT/CBSE Class 12th Chemistry Paper Code (HSEIIRKO-9318–C)
Question: How will you convert
(i) Benzoic acid into Benzoyl alcohol
(ii) Benzoic acid into Benzoyl anhydride
(iii) Acetic acid into propanoic acid
(iv) Benzoic acid into oxalic acid.
Answer: (i) Benzoic acid can be converted into Benzoyl alcohol through a reaction of benzoic acid with hydroxide anion and a proton-transfer catalyst.
(ii) Benzoic acid can be converted into Benzoyl anhydride through a reaction of benzoic acid with anhydrous hydrogen chloride.
(iii) Acetic acid can be converted into propanoic acid through a reaction of acetic acid with a base, such as potassium hydroxide, to form potassium acetate, followed by a reaction of the potassium acetate with a nucleophile, such as a Grignard reagent.
(iv) Benzoic acid cannot be directly converted into oxalic acid. Oxalic acid can be synthesized from benzoic acid by first converting benzoic acid into benzaldehyde through a reaction with a base, followed by a reaction of the benzaldehyde with a halogenating agent, such as chlorine or bromine, to form benzyl chloride. Benzyl chloride can then be reacted with an alcohol in the presence of an acid catalyst to form oxalic acid.
Question: Explain Frankel defect in ionic crystals. What type of compound exhibit this defect?
Answer: Frankel defect is a type of point defect in an ionic crystal that occurs when a lattice site is left vacant due to the absence of an anion or cation. This results in a net electrical charge in the crystal, which can affect the electrical and optical properties of the material.
This type of defect is often observed in compounds containing ions of different sizes, such as alkali halides and oxide compounds, where the larger ions cannot fit into the same lattice sites as the smaller ones.
Question: How will you prepare chloroform from Etanol.
Answer: To prepare chloroform from ethanol, you need to mix the ethanol with a strong acid such as hydrochloric acid. This mixture will be heated to a temperature of around 100 degrees Celsius, which will cause the ethanol to react with the acid and produce chloroform. The chloroform can then be separated from the acid using distillation.
Question: What is relationship between Gibb’s free energy change and cell potential.
Answer: The Gibbs free energy change is directly related to the cell potential. The cell potential determines the amount of mechanical work that can be done on the system and is related to the Gibbs free energy change by the equation
ΔG = -nFE, where n is the number of moles of electrons transferred, F is the Faraday constant, and E is the cell potential.
The Gibbs free energy change represents the maximum amount of mechanical work that can be extracted from the system and is calculated by taking into account the temperature and the change in entropy. Thus, the cell potential is directly related to the Gibbs free energy change.
Question: What are Antifertility drugs? Give an example.
Answer: Antifertility drugs are medications that are used to reduce the chances of pregnancy. One example of an antifertility drug is the birth control pill, which is a combination of synthetic hormones that prevent ovulation.
Question: What is meant by Hexagonal close packing in three dimensions.
Answer: Hexagonal close packing in three dimensions is a type of close packing of equal spheres in which each sphere is surrounded by six other spheres in the same plane and each sphere is in contact with twelve other spheres. This arrangement is the densest possible arrangement of spheres in three dimensions.
Question: Define Geometric Isomerism
Answer: Geometric isomerism is a type of stereoisomerism that occurs when two or more molecules have the same molecular formula and molecular structure, but the spatial arrangement of atoms within the molecule differs. This type of isomerism is most common in compounds with double bonds, but can also occur in compounds with single bonds.
Question: Describe secondary Structure of proteins
Answer: Secondary structure of proteins refers to the regular local structural motifs that occur within a polypeptide chain, such as alpha helices, beta sheets, and turns. These are formed by hydrogen bonding between the backbone of the chain and the side chains of the amino acids. Secondary structure can have a major influence on the conformation, activity, and stability of the protein.
Question: What are biodegradable polymers. Write the structural formulae of a biodegradable polymer
Answer: Biodegradable polymers are polymers that can be broken down by microbial action and natural environmental processes over time. Examples include polylactic acid (PLA) and polyhydroxyalkanoate (PHA).
The structural formula of polylactic acid (PLA) is: (C3H4O2)n
The structural formula of polyhydroxyalkanoate (PHA) is: (C3H6O2)n
Objective Type Questions (Each carries 1 Marks)
(i) The co-ordination numberof each sphere in a body centred close packed structure is —————–
Answer: 12
(ii) Acid chlorides are reduced to aldehydes by ———— reaction
Answer: Hydrogenation
(iii) Benedicts solutionis used to determine glucose in blood. (True/False)
Answer: True
(iv) Oxygen shows an oxidation state of +4 and +6 like sulphur
Answer: True
(v) The substance which donot help in the formation of Froth in Froth floatation process is called ——————-
Answer: Depressant
(vi) The sweetener which is 600 times sweetner than sucrose is known as ————-
Answer: Sucralose
(vii) Name the most common refrigerant and give its formula
Answer: The most common refrigerant is R-134a, which has the chemical formula, CH2FCF3.
(viii) Which type of property is Brownian moment in a colloidal solution
Answer: Brownian moment in a colloidal solution is a type of kinetic property.
(ix) Reaction of C6H5N2Cl with CuCl gives.
Answer: CuCl2(C6H5N2).