A radioactive element has a half life of 200 days. The percentage of original activity remaining after 83 days is ___________. (Nearest integer)

(Given : antilog 0.125 = 1.333, antilog 0.693 = 4.93)

$${[Fe{(CN)_6}]^{4 - }}$$

$${[Fe{(CN)_6}]^{3 - }}$$

$${[Ti{(CN)_6}]^{3 - }}$$

$${[Ni{(CN)_4}]^{2 - }}$$

$${[Co{(CN)_6}]^{3 - }}$$

Among the given complexes, number of paramagnetic complexes is ____________.

(a) CoCl₃.4NH₃,    (b) CoCl₃.5NH₃,      (c) CoCl₃.6NH₃    and    (d) CoCl(NO₃)₂.5NH₃.

Number of complex(es) which will exist in cis-trans form is/are _______________.

The complete combustion of 0.492 g of an organic compound containing 'C', 'H' and 'O' gives 0.793 g of CO₂ and 0.442 g of H₂O. The percentage of oxygen composition in the organic compound is ______________. (nearest integer)