Answer:
I am owned by every man though my length differs. Their wives uses me after getting married.
I am black within and red without; with four corners round about. What am I?
I start new then become old. Start clean but become dirty. I usually start big then become little. What am I?
I am the ultimate killing machine used not once but TWICE I can be made by humans.
I am a seed with three letters in my name. Take away the last two and I still sound the same.
What is lighter than what it is made of?