With respect to the properties of hydrides of group 15, the total number of correct trends is(are) :
$i.$ Basic strength:
${\mathrm{NH}}_3>{\mathrm{PH}}_3>{\mathrm{AsH}}_3>{\mathrm{SbH}}_3\ge {\mathrm{BiH}}_3$
$ii.$ Boiling point:
${\mathrm{NH}}_3<{\mathrm{PH}}_3<{\mathrm{AsH}}_3<{\mathrm{SbH}}_3<{\mathrm{BiH}}_3$
$iii.$ Thermal stability:
${\mathrm{NH}}_3>{\mathrm{PH}}_3>{\mathrm{AsH}}_3>{\mathrm{SbH}}_3>{\mathrm{BiH}}_3$
$iv.$Reducing character:
${\mathrm{NH}}_3<{\mathrm{PH}}_3<{\mathrm{AsH}}_3<{\mathrm{SbH}}_3<{\mathrm{BiH}}_3$