How do you decide wether a sample of matter is a soild, liquid, or gas

Which diagram shows the correct way to represent an ionic compound of magnesium oxide?

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Precision can be defined as the o exact center of a data set. o reproducibility of a measured value. o correlation between two variables that are measured in a data set agreement between a measured value and an accepted value.