Arrange the measurements from least to greatest. 1.8 micrograms 1.8 grams 1.8 milligrams 1.8 kilograms

The order follows:  

Explanation:

Gram is unit which is used to expressed mass of a substance. Many other units can be used to express the mass of a substance. All the units are inter changeable.

For the given values:

Conversion factor from Gram to micro gram

So,

All other units are expressed in this standard unit of mass and then, it will be compared.

Conversion factor from Gram to mili gram

So,

Conversion factor from Gram to mili gram

So,

Hence, the order follows:  

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.