The metal d-orbitals that are directly facing the ligands in K₃[Co(CN)₆] are -

What is the work function of the metal if the light of wavelength 4000$$\mathop A\limits^ \circ $$ generates photoelectrons of velocity 6 $$ \times $$ 10⁵ ms^–1 from it ?
(Mass of electron = 9 $$ \times $$ 10^–31 kg;
Velocity of light = 3 $$ \times $$ 10⁸ ms^$$-$$1
Plank's constant = 6.626 $$ \times $$ 10^–34 Js;
Charge of electron = 1.6 $$ \times $$10^–19 JeV^–1)

The hardness of a water sample (in terms of equivalents of CaCO₃) containing 10^–3 M CaSO₄ is (Molar mass of CaSO₄ = 136 g mol^–1)

Freezing point of a 4% aqueous solution of X is equal to freezing point of 12% aqueous solution of Y. If molecular weight of X is A, then molecular weight of Y is -