Answer:
I will disappear every time you say my name.
I'm tall when I'm young and I'm short when I'm old. What am I?
I am just two and two. I am hot. I am cold. I am the parent of numbers that cannot be told. I am a gift beyond measure, a matter of course. What am I?
I am as hard as metal, yet as flimsy as glass. I shine like a star, yet I am only a rock. What am I?
The warmer I am, the fresher I am. What am I?
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.