I am as hard as a rock but I will immediately melt in water. What am I

(a)  

What has to be broken before you can use it

(a)  

I am tall when I am Young and I am short when I am Old

(a)  

Which Month has 28 days?

(a)  

What is always in front of you but can’t be seen?

(a)  

What can’t talk but will reply when spoken to?

(a)