IGNOU BCHET-147 December 2023 Previous Year Question Paper

Q1.Identify the l igands which form complex with Cr, Mn, Co and Cu, in low oxidation states. [ 2 ] BCHET–147 What is the nature of the compounds in terms of oxidizing reducing behaviour when the metals are in high er or in lower oxidation states ?

Q2.Which type of elements form σ-bonded organometallics ? Do transition metals form such compounds ? Give suitable examples. Also give an example of such a compound present in nature and mention the σ -bond in it.

Q3.Give the formal charge and the number of electrons donated by these ligands in organometallic compounds :

Q4.What conclusions about the strength of the M-C bond can be drawn from the following data of metal carbonyl stretching frequencies ? 5 Metal Carbonyl MC  6Mn CO 416 cm–1  6Cr CO 441 cm–1  6V CO 460 cm–1 [ 3 ]

Q5.What is antagonism in reference to metals in biological system ? Explain with the help of an example involving copper . What happens as a result of copper deficiency ?

Q6.Give the general principle of the Na +-K+ pump.

Q7.Why is it considered to be a case of active transport ?

Q8.Give any five biological processes in which the trace element iron is involved in the living system. 5 Part—B (Marks : 25)

Q9.Discuss the mechanism of synthesis of ethyl 3 - oxobutanoate using Claisen ester condensation.

Q10.(a) Write the IUPAC names of the following compounds : 2 [ 4 ] BCHET–147

(b) Write the products (i. e. A, B and C) of the following reactions :

Q11.(a) Explain the formation of 2 -aminopyridine when pyridi ne reacts with NaNH 2. Write the mechanism of this reaction. 3

(b) How is pyridi ne obtained commercially ? Give the reaction involved.

Q12.Define the following terms : 5

(a) Wavelength

(b) Wave number

(c) Frequency of a wave

Q13.The absorption bands of the two chromophores are given below : acetylene : 152 nm (s), 182 nm (m), 220 nm (w) benzene : 184 nm (s), 204 nm (m), 254 nm (w) What sort of transitions can be predicted for these ? 5 [ 5 ]

Q14.In the 2500 -2000 cm –1 region of the IR spectrum, why a greater intensity of band for N is observed than for – C  C – group ?

Q15.(i) Can you identify symmetrical alkynes with the help of IR spectroscopy ? Justify your answer. 2

(ii) With the help of IR spectra , can you differentiate between cyclohexane and hexanol ? Justify your answer. 3 [ 6 ] BCHET–147 2023 -147

(ii) Cr, Mn, [ 7 ] BCHET–147 MC  6Mn CO 416 cm–1  6Cr CO 441 cm–1  6V CO 460 cm–1 [ 8 ] BCHET–147 (antagonism) [ 9 ] BCHET–147 A, B 2NaNH [ 10 ] BCHET–147 CN 1cm (hexanol)