Maharashtra State Board
- The IUPAC name of [Co(NH3)5Cl]Cl2 is Answer: C. pentaamminechloridocobalt(III) chloride Cation complex: x+0-1=+2⇒ Co(III). Ligands are named alphabetically (ammine before chlori... 1
- [Ni(CN)4]2− is diamagnetic. Its hybridisation and geometry are Answer: D. dsp2, square planar Ni²⁺ is 3d⁸. Strong-field CN⁻ pairs the electrons, leaving one 3d orbital free for dsp² (square planar, diama... 1
- The total number of stereoisomers of [Co(en)2Cl2]+ is Answer: D. 3 Trans form is optically inactive (1); cis form is chiral and exists as a pair of enantiomers (2). Total =3 . 1
- Which of the following undergoes SN1 reaction fastest? Answer: D. (CH3)3CBr S_N1 rate depends on carbocation stability; the tertiary carbocation is the most stable. 1
- Chlorobenzene reacts with methyl chloride and sodium in dry ether. The main product is Answer: C. toluene Wurtz–Fittig reaction: C₆H₅Cl+CH₃Cl+2Na→ C₆H₅CH₃+2NaCl . 1
- Phenol reacts with bromine water to give Answer: B. 2,4,6-tribromophenol In polar water, phenol is strongly activated and is brominated at all o- and p-positions, giving a white pre... 1
- Which alcohol gives turbidity immediately with Lucas reagent at room temperature? Answer: A. 2-methylpropan-2-ol Tertiary alcohols react immediately with conc. HCl/ZnCl₂ through a stable carbocation; 2-methylpropan-2-ol is... 1
- Anisole on heating with HI gives Answer: A. phenol and methyl iodide The O–C(aryl) bond has partial double-bond character and is not cleaved. I⁻ attacks the methyl group (S_... 1
- Which of the following undergoes the Cannizzaro reaction? Answer: D. Benzaldehyde The Cannizzaro reaction needs an aldehyde with no α-hydrogen; benzaldehyde has none. 1
- The strongest acid among the following is Answer: C. Cl3CCOOH Three −I chlorine atoms stabilise the carboxylate ion the most. 1
- Acetophenone on Clemmensen reduction (Zn–Hg / conc. HCl) gives Answer: D. ethylbenzene Clemmensen reduction converts >C=O to >CH₂: C₆H₅COCH₃ → C₆H₅CH₂CH₃. 1
- Which of the following is the strongest base in aqueous solution? Answer: C. (CH3)2NH In water, inductive effect, solvation and steric factors combine to give (CH₃)₂NH > CH₃NH₂ > (CH₃)₃N; aniline is much we... 1
- Acetamide on treatment with Br2 and aqueous NaOH gives Answer: D. methanamine Hofmann bromamide degradation gives a primary amine with one carbon fewer: CH₃CONH₂ → CH₃NH₂. 1
- On prolonged heating with HI, glucose gives n-hexane. This shows that glucose Answer: B. has all six carbon atoms in a straight chain Complete reduction to n-hexane shows that the six carbons form an unbranched chain. 1
- Which of the following reactions has 100% atom economy? Answer: B. CH2=CH2 + H2 → C2H6 In an addition reaction all reactant atoms end up in the product, so the atom economy is 100%. 1
- The number of molecules in 4.4 g of CO2 is Answer: A. 6.022×10²² n=4.4/44=0.1 mol ⇒0.1×6.022×10²³ molecules. 1
- A compound contains 40% C, 6.67% H and 53.3% O by mass. Its empirical formula is Answer: D. CH2O Mole ratio C : H : O =40/12:6.67/1:53.3/16=3.33:6.67:3.33=1:2:1 . 1
- The number of radial nodes in a 3p orbital is Answer: B. 1 Radial nodes =n-l-1=3-1-1=1 . 1
- The maximum number of electrons in an atom that can have \(n=3\) and \(m_s=+\frac12\) is Answer: B. 9 The n=3 shell has n²=9 orbitals, and each holds one electron with m_s=+1/2 . 1
- The bond order of the superoxide ion O2− is Answer: D. 1.5 O₂⁻ has 17 electrons: bonding 10, antibonding 7. Bond order =10-7/2=1.5 . 1
- The shape of the ClF3 molecule is Answer: B. T-shaped Cl has 3 bond pairs and 2 lone pairs (sp³d). The lone pairs occupy equatorial positions, giving a T-shape. 1
- The oxidation number of oxygen in OF2 is Answer: A. +2 F is always −1: x+2(-1)=0⇒ x=+2 . 1
- Under identical conditions, the ratio of the rates of effusion of H2 and O2 is Answer: B. 4 : 1 Graham's law: fracr_(H_2)r_(O_2)=√(32/2)=4 . 1
- Ozonolysis of but-2-ene followed by treatment with Zn/H2O gives Answer: A. two molecules of ethanal CH₃CH=CHCH₃ is cleaved at the C=C bond to give 2 CH₃CHO. 1