1. Una propiedad de la materia es que posee masa, y en el átomo no hay excepción a pesar de su tamaño infinitamente pequeño. Cuando la masa atómica de un elemento se expresa en gramos, se obtiene una magnitud denominada:​

7. describe two strategies that parents can use to cope with stress. 8. describe the three types of childcare available to families. 9. what can parents do to be more involved in their children's education at home and at school? 10. which factors should a parent consider when choosing a childcare option?