Just realized something about climbing ropes.

Today I noticed while in bleak inlet that the ropes weigh 5 kgs. A rope.. I understand its heavy duty but ropes are usually quite light like 2 kgs max and rarely. It's made of paracord so artificial materials and paracord is light usually so why. To put in perspective a modern day hunting rifle probably weighs 2-5 kgs with extra clips/ rounds/ magazines. So why hinterland why. Are these ropes secretly chains covered by thin rope covering?