Could you please help me

What is the number of moles in 15.0 g ash3?

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

What does the symbol (–hfus) indicate in a phase change?