How many moles are in 2.1 x 10^{24} molecules SiO4

3.5 moles

Explanation:

Based on Avogadro's law:

1 mole of any substance has 6.02 x 10^23 molecules

So, 1 mole of SiO4 = 6.02 x 10^23 molecules

Zmoles of SiO4 = 2.1 x 10^{24} molecules

To get the value of Z, cross multiply:

(2.1 x 10^{24} molecules x 1mole) = (6.02 x 10^23 molecules x Z moles)

2.1 x 10^{24} molecules = (6.02 x 10^23 x Z)

Z = (2.1 x 10^{24}) ➗ (6.02 x 10^23)

Z = 3.5 moles

Thus, there are 3.5 moles of SiO4.

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance