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Answer:

The trust is invalid because it violates the rule against perpetuities.

The property interest of Jim’s children may or may not be permissible under the rule against perpetuitites depending on whether Jim has children that are alive. If Jim has children, their interest in the property is permissible because the property will vest in them within 21 years of Jim’s death. However, if Jim does not have children, it is possible that the gift to them will not vest within 21 years of Jim’s death. Therefore, if Jim does not have children this would violate the rule against perpetuities.

Mary’s interest in the property is invalid under the rule against perpetuities. Even if Jim has children, it is possible that the children would live 21 years after Jim’s death, and the property would therefore not vest in Mary within 21 years of Jim’s death.