¿Cuántos mol contienen 279 g de hierro metálico?

What volume of a 2.00 m stock solution of naoh is needed to prepare 150. ml of 0.40 m solution?

8.98 dm3 of hydrogen gas is collected at 38.8 °c. find the volume the gas will occupy at -39.9 °c if the pressure remains constant.

Is a pencil falling to the floor anon contact force, a force, or a contact force