Stability of $$\alpha$$-Helix structure of proteins depends upon

The formula of the purple colour formed in Laissaigne's test for sulphur using sodium nitroprusside is :

A 2.0 g sample containing MnO₂ is treated with HCl liberating Cl₂. The Cl₂ gas is passed into a solution of KI and 60.0 mL of 0.1 M Na₂S₂O₃ is required to titrate the liberated iodine. The percentage of MnO₂ in the sample is _____________. (Nearest integer)

[Atomic masses (in u) Mn = 55; Cl = 35.5; O = 16, I = 127, Na = 23, K = 39, S = 32]

If the work function of a metal is 6.63 $$\times$$ 10^$$-$$19J, the maximum wavelength of the photon required to remove a photoelectron from the metal is ____________ nm. (Nearest integer)

[Given : h = 6.63 $$\times$$ 10^$$-$$34 J s, and c = 3 $$\times$$ 10⁸ m s^$$-$$1]