Here are the perks challenges:
Lightweight Challenges:
Escape death 5 times after being shot
Get 15 melee kills
Get 10 offense medals by killing ops near their objectives

Scavenger Challenges:
Get 2 kills without dying
Get 10 lethal grenade kills with resupplied grenades
Resupply 150 times with scavenger

Ghost Challenges:
Destroy 30 aircraft without killstreaks
Destroy 5 sentry guns
Kill 20 enemies while their spy plane or blackbird is up

Flak Jacket:
Plant/defuse 10 bombs in demolition
Survive 10 explosions
Throw back 5 enemy grenades

Hardline:
Earn and call in attack dogs
Get a 7 killstreak
Share 10 care packages with teammates

Hardened:
Get 30 kills through walls
Destroy 10 pieces of enemy equipment through walls
Shoot 200 bullets into enemy aircraft

Scout:
Get 30 headshots
Get 50 one shot one kills
Get 50 kills with secondary weapons

Steady Aim:
Get 150 hip-fire kills
Melee 2 enemies consecutively 3 times
Get 100 kills after sprinting

Sleight of Hand:
Get 150 kills while ADS
Reload and finish off the enemy you wounded 10 times (shoot, reload, kill X10)
Kill an enemy within 5 seconds of reloading 30 times

Warlord:
Get 25 frag or semtex kills
Get 5 multi-kills with grenades
Get 150 kills using guns with two attachments

Marathon:
Capture 15 flags
Get first blood 10 times
Run 26 miles using marathon

Ninja:
Get 15 backstabber medals
Plant the bomb in search and destroy 10 times
Get 150 kills using the suppressor attachment

Second Chance:
Get 3 headshot kills in second chance
Get 20 kills in second chance
In second chance, kill the guy who downed you 5 times

Hacker:
Destroy 25 equipment or explosives using hacker
Kill an enemy with claymores or c4 25 times
Kill 25 enemies within jammer or motion sensor radius

Tactical Mask:
Kill 20 enemies that are stunned by your concussion grenade
Kill 20 flashbanged enemies by your flashbang
Kill 20 enemies poisoned by your nova gas