Can anyone help please?

100mg magnesium reacts with 20ml of 1.0m hcl

If 1.63 times 10 negative 4 of helium dissolves in 100.0g of water, what is the concentration in parts per million

Identify one disadvantage to each of the following models of electron configuration: -dot structures -arrow and line diagrams -written electron configurations type in your answer below. (answer) -dot structures do not show the distribution of electrons in orbitals and take up a lot of space. -arrow and line diagrams take up a lot of space and make it difficult to count electrons. -written configurations make it easy to lose count of electrons and do not show the distribution of electrons in orbitals.