Find the number of following reactions which are involved in roasting process :
(i) `S_(8) + 8 O_(2) overset (Delta)rarr 8SO_(2) uarr`
(ii) `P_(4) + 5O_(2) overset (Delta) rarr P_(4) O_(10) uarr`
(iii) `4 As + 3O_(2) overset (Delta) rarr 2 As_(2) O_(3) uarr`
(iv) `2ZnS + 3 O overset (Delta) rarr 2 ZnO + 2SO_(2) uarr`
(v) `ZnCO_(3) overset (Delta) rarr 4 ZnO + CO_(2) uarr`.

Answer

`(4)`

Explanation

Roasting is heating the ore in presence of `O_(2)`. Reactions (i),(ii),(iii) and (iv) can be termed roasting.