The spin-only magnetic moment value of M³⁺ ion (in gaseous state) from the pairs Cr³⁺ / Cr²⁺, Mn³⁺ / Mn²⁺, Fe³⁺ / Fe²⁺ and Co³⁺ / Co²⁺ that has negative standard electrode potential, is ____________ B.M. [Nearest integer]

A sample of 4.5 mg of an unknown monohydric alcohol, R-OH was added to methylmagnesium iodide. A gas is evolved and is collected and its volume measured to be 3.1 mL. The molecular weight of the unknown alcohol is __________ g/mol. [Nearest integer]

The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front, substance A and substance B from the base line are 3.25 cm, 2.08 cm and 1.05 cm, respectively. The ratio of R_f values of A to B is _____________.

The total number of monobromo derivatives formed by the alkanes with molecular formula C₅H₁₂ is (excluding stereo isomers) __________.