Decomposition of X exhibits a rate constant of 0.05 $$\mu $$g/year. How many year are required for the decomposition of 5$$\mu $$g of X into 2.5 $$\mu $$g?

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)