Identify the correct statements from the following .
(i) Oxygen shows -2,-1,+1 and +2 oxidation states.
(ii) The thermal stability of `H_(2)O, H_(2)Se` and `H_(2)S` follows the order `H_(2)O ltH_(2)S lt H_(2)Se.`
(iii) The reducing nature of `H_(2)Se,H_(2)S` and `H_(2)` Te follows the order `H_(2)S ltH_(2)Se ltH_(2)Te`

Options

A. I,ii,iii
B. I,ii
C. I,iii
D. ii,iii

Answer

C

Explanation

Oxygen shows -2-1 +1 and +2 oxidation states.
(i) Oxygen shows -2 Oxidation states in most of its compound while it shows (-1) O.S in peroxides ( like `H_(2)O_(2)),+` 1 in `O_(2)F_(2)` and +2 in `OF_(2)` . Thus it show -2,-1 ,+1 and +2 oxidation states .
(ii) The thermal stability of `H_(2)O, H_(2)` Se and `H_(2)S` follows the order `H_(2)O gt H_(2)S gt H_(2)Se `
This is because on going down the group the size of the central atom increases and therefore its tendency to form stable covalent bond with hydrogen decreases . As a result the M-H bond strength decreases and therefore thermal stability decreases
(iii) The reducing nature of `H_(2)SeH_(2)S` and `H_(2)` Te follows the order
`H_(2) lt H_(2)Se lt H_(2)Te`
This is due to the decrease in thermal stability of the hydride greater the unstability of hydrides the greater is its reducing character.