Which of the following reaction/s will not give p-aminoazobenzene?

Using the provided information in the following paper chromatogram :


Fig : Paper chromatography for compounds A and B.

the calculated R_f value of A ________$$\times$$ 10^-1.

The reaction of cyanamide, NH₂CN_(s) with oxygen was run in a bomb calorimeter and $$\Delta$$U was found to be $$-$$742.24 kJ mol^$$-$$1. The magnitude of $$\Delta$$H₂₉₈ for the reaction

$$N{H_2}C{H_{(S)}} + {3 \over 2}{O_{2(g)}} \to {N_{2(g)}} + {O_{2(g)}} + {H_2}{O_{(I)}}$$

is _________ kJ. (Rounded off to the nearest integer) [Assume ideal gases and R = 8.314 J mol^$$-$$1 K^$$-$$1]

The ionization enthalpy of Na⁺ formation from Na_(g) is 495.8 kJ mol^$$-$$1, while the electron gain enthalpy of Br is $$-$$325.0 kJ mol^$$-$$1. Given the lattice enthalpy of NaBr is $$-$$728.4 kJ mol^$$-$$1. The energy for the formation of NaBr ionic solid is ($$-$$) ____________ $$\times$$ 10^$$-$$1 kJ mol^$$-$$1.