Trudy's will contains the following provisions

1.I appoint Ernie as sole executor of my will and trustee of my estate.

2.I give $100,000 to Ernie

3.I give $500,000 to my old school, St Scholastica's College, for the construction of a new gymnasium.

4.I give the residue of my estate to Ernie on trust to be divided into equal shares among such of my grandchildren who attain the age of 25 years.

Discuss the validity of clauses 2, 3 and 4.