The major product in the following reaction is:

Complexes (ML₅) of metals Ni and Fe have ideal square pyramidal and trigonal bipyramidal grometries, respectively. The sum of the 90°, 120° and 180° L-M-L angles in the two complexes is ________.

For an electrochemical cell

Sn(s) | Sn²⁺ (aq,1M)||Pb²⁺ (aq,1M)|Pb(s)

the ratio $${{\left[ {S{n^{2 + }}} \right]} \over {\left[ {P{b^{2 + }}} \right]}}$$ when this cell attains equilibrium is _________.

(Given $$E_{S{n^{2 + }}|Sn}^0 = - 0.14V$$,

$$E_{P{b^{2 + }}|Pb}^0 = - 0.13V$$, $${{2.303RT} \over F} = 0.06$$)

Arrange the following bonds according to their average bond energies in descending order :
C–Cl, C–Br, C–F, C–I