What do all pure substances have in common? A. They cannot be broken into smaller pieces. B. They are made up of atoms or groups
1 answer:
Answer: The correct option is B.
Explanation: Pure substances are defined as the substances which are made up of one one type of atom or a molecule. Example: Iron (Fe), etc.
Option A: These substances can be cut into smaller pieces because only the size of the substance is changing.
Option B: All the pure substances are made up of atoms and group of atoms known as molecules. So, this is common to all the pure substances.
Option C: These substances can be mixed with other substance. For example: Iron can be mixed with another Copper.
Option D: These substances when undergoing a chemical reaction will change its chemical composition.
Hence, the correct option is B.
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Answer:
The compound is N2O4
Explanation:
We have certain important pieces of information about the compound;
1) it is an oxide (a binary compound of nitrogen and oxygen)
2) there are no N-N bonds present
3) there are no O-O bonds present
Since it contains only nitrogen and oxygen then nitrogen accounts for 25.9% of the molecule by mass then oxygen should account for (100-25.9) = 74.1% oxygen
Relative atomic mass of oxygen = 16
Relative atomic mass of nitrogen = 14
We now deduce the empirical formula
Nitrogen. Oxygen
25.9/14. 74.1/16
1.85/1.85. 4.6/1.85 (divide through by the lowest ratio)
1 2
Empirical formula is NO2
To find the molecular formula
(NO2)n = 108
(14+2(16))n= 108
46n=108
n= 108/46
n= 2
Therefore molecular formula= N2O4
