IGNOU BCHCT-137 December 2025 Previous Year Question Paper

Q1.(a) Explain the ground state electronic configuration of Sct+ ion. 2

(b) Complete and balance any two of the following reactions :

Q2.(a)

(i) Which of the following ions is coloured ? Give reasons : 2

(1) TA F 3

(ii) What is the unit of magnetic moment ? 1

(b) Name any two transition elements which are present in very small quantities in plants and animals and are essential for the enzymes to function ?

Q3.(a) Which one of the following complexes does not have perfect octahedral geometry ? Justify your answer : 3 G@) [Cr(H20)6]3*

(0) [VCle6]2-

(iii) [Fe(H20)6]

(b) Calculate the spin-only magnetic moment for [Mn(H20)¢]2+ or CuCl.

Q4.(a) Why is the size of the elements of third transition series almost similar to that of the elements of second transition series ? 3

(b) Determine the oxidation state and coordination number of the central metal ion in the following : 2 @ [Ag(NHs)2]*

(ii) [Co(H20)6]?*

Q5.(a) Write the IUPAC name of any one of the following compounds :

Q6.. [(NHs)s CoNH2 . Co(NHs3)s] (NOs)s

(ii) [(CO)3 Fe(CO)3 Fe(CO)s]

(b) Write down all possible isomers of [Co(NH3)sNO2]Cl2 and give their names.

Q7.(a) Write the formula of the following:

Q8.Tetrapyridineplatinum (I) Tetra- chloridoplatinate (II) Gi) Petaammineaquacobalt (II) chloride

(b) Explain the structure and magnetic moments of the following complexes on the basis of valence bond theory : 3 [MnCli]2- and [Mn(CN).]®-

Q9.(a) Calculate the crystal field stabilization energy of [Fe(CN)«]* complex. 3

(b) What is spectrochemical series ? 2 Part—B (Marks : 25) (States of Matter and Chemical Kinetics)

Q10.(a) State Boyle’s law and draw a graph between P and 1/V for an ideal gas. 2

(b) The density of a gas was found to be

Q11.43 g/L at 300 K and 1 atm. Calculate the molecular mass.

Q12.(a) 2 mole of Ne and 3 mole of He gas are kept in a container. The total pressure is 10 atm. Find out the partial pressure of Hz and Ne. 3

(b) What is most probable velocity (vmp) ? Explain with graph of Maxwell- Boltzmann’s distribution.

Q13.(a) Why are bubbles of a gas spherical in nature ? 1

(b) What is the effect of temperature on surface tension ? 1

(c) The number of drops for a certain volume of water counted in a stalgamometer at 298 K is 300, whereas the number of drops for the same volume of ethy] alcohol is 320. Calculate the surface tension of ethyl alcohol. Given that : 3 The density of water = 0.998 kg dm-3 Density of ethyl alcohol = 0.9614 kg dm? Surface tension of water = 0.0727 Nm!

Q14.(a) Illustrate the formation of a tetrahedral void and an octahedral void. 3

(b) Calculate the number of formula units of NaCl present in a unit cell of NaCl.

Q15.(a) Silver has a fec lattice. The edge length of its unit cell is 4.077 x 10-8 cm and its density is 10.12 g/em*. What is the molar mass of silver ? 3

(b) Give two differences between Schottky defect and Frenkel defect.

Q16.(a) State law of constancy of interfacial angles. 1

(b) What are pseudo first order reactions ? Give an example. 2

(c) “Molecularity of a reaction rarely exceeds 3.” Explain.

Q17.(a) Derive the expression for integrated rate law for a zero-order reaction. 3

(b) Draw the following plots for a first order reaction : 2

(ii) log Hol us. t

(i) 710) + 0५

(8) 2 a 2

(i) [VCl6]2-

(iii) [Fe(H20)6]* (@) [Mn(H20)6]2+ @ CuCl & fae axa

Q18.[Ag(NHs)2]*

(ii) [Co(H20)6]2*

(i) [(NHs3)5 CoNHe . Co(NHs)s] (NOs)s

(ii) [(CO)3 Fe(CO)3 Fe(CO)s] [Co(NH3)sNO3] Cle & at dented wares [MnCli]2- 3% [Mn(CN)¢]3- We I FAA = 0.998 kg dm-3 We I YS TAA = 0.0727 Nm!

(ii) log Ft us. t