The answer is 3). This is because elements are the simplest form of a substance, and cannot be broken down any further. Compounds on the other hand are much more complex than elements and can be broken down INTO elements.
For example, Na, sodium, is an element and cannot be broken down further. H2O, water, is a compound and can be broken down into Hydrogen and Oxygen.
Answer:
<u>2.26 </u>
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Explanation:
First you should know what are significant figures,
1 . All non - zero digits are significant.
2 . The zero between two non- zero are significant.Ex 302 has 3 significant figures.
3. The zero before the decimal and before any non-zero digit is non significant. Example : 0.003 has only 1 significant figure.
4. The zero after non zero are non - significant . But the zeros after the decimal point are significant.
300 has only 1 significant figure
300.0 has 4 significant figure
The least number of significant figures present in the number should be there in the final answer of the calculation.
Look at the number having minimum significant digits :
It is 3 (every number has 3- significant figures ) So the answer should also contain 3 - significant figures.

First solve the numerator part


Round off this number to 3 significant figures.
Answer is =<u> 2.26</u>
It has 3 - significant digit since all the digits are non-zero.
8.04 mL.
<h3>Explanation</h3>
How many moles of NaOH?
Note the unit:
.
.
How many moles of HCl?
As seen in the equation, HCl and NaOH reacts at a 1:1 ratio.
.
How many mL of HCl?
.
It could not hold good for elements heaver than calcium.
Answer:
2,780,000mg
Explanation:
Using the Metric Staircase photo provided, you can calculate how many mg there are in 2.78 kg by simply moving the decimal point six places to the right, since the "Kilo" step takes six places to move to the "Milli" step.
2.78 kg
---------------
2 7 8 0 0 0 0 .
we can see that the decimal point is moved to the right six places.
Answer:
2,780,000mg