Answer:
Which is the oldest tree?
People in love are often bound to this.
Is always in front of you but cannot be seen?
White and thin, red within, with a nail at the end. What is it?
Take one royal word in the plural and make it singular by adding one letter
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.