Minecraft Scoreboard Item give Tag Problem [duplicate]
When testing for NBT data, you need to match exactly, including the data's type.
As Count is a byte rather than an integer, you need to append b:
/scoreboard players tag @e[type=Item] add T1 {Item:{id:"minecraft:tnt",Count:1b}}
/scoreboard players tag @e[type=Item] add T2 {Item:{id:"minecraft:arrow",Count:1b}}