An organic (covalent) compound is determined to contain 25.54% carbon, 6.43% hydrogen, and 68.03% oxygen. The molar mass of this compound is 141.099. What is the molecular formula of this compound?

https://courses.lumenlearning.com/sanjacinto-atdcoursereview-chemistry1-1/chapter/formula-mass-and-the-mole-concept/

Explanation:

https://courses.lumenlearning.com/sanjacinto-atdcoursereview-chemistry1-1/chapter/formula-mass-and-the-mole-concept/

the answer should be in there

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

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