Answer: Depending on the data and the patterns, sometimes we can see that pattern in a simple tabular presentation of the data. Other times, it helps to visualize the data in a chart, like a time series, line graph, or scatter plot.
Explanation:
1960 5.91
1970 5.59
1980 4.83
1990 4.05
2000 3.31
2010 2.60
The subscript 2 in the formula o2 indicates that there are 2 atoms of the element oxygen, represented by the symbol "O." The subscript to the right of the symbol tells how many atoms are present of that element.
Answer:

Explanation:
<u>1. Convert Molecules to Moles</u>
First, we must convert molecules to moles using Avogadro's Number: 6.022*10²³. This tells us the number of particles in 1 mole of a substance. In this case, the particles are molecules of sodium hydroxide.

Multiply by the given number of molecules.

Flip the fraction so the molecules cancel out.




<u>2. Convert Moles to Grams</u>
Next, we convert moles to grams using the molar mass.
We must calculate the molar mass using the values on the Periodic Table. Look up each individual element.
- Na: 22.9897693 g/mol
- O: 15.999 g/mol
- H: 1.008 g/mol
Since the formula has no subscripts, we can simply add the molar masses.
- NaOH: 22.9897693+15.999+1.008=39.9967693 g/mol
Use this as a ratio.

Multiply by the number of moles we calculated.

The moles of sodium hydroxide cancel.



The original measurement of molecules has 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place. The 0 tells us to leave the 7 in the hundredth place.

1.20*10²² molecules of sodium hydroxide is approximately 0.797 grams.
Answer: Valence electron
Explanation:
The elements in each group have the same number of electrons in the outer orbital. Those outer electrons are also called valence electrons. They are the electrons involved in chemical bonds with other elements.
H₂ is the limiting reactant.
<u>Explanation:</u>
H₂ reacts with O₂
The reaction would be
2H₂ + O₂ → 2H₂O
According to the balanced equation, 2 moles of H₂ reacts with 1 mole of O₂ to form 2 moles of H₂O.
The ratio of usage of H₂ and O₂ is 2 : 1 respectively
If 3 moles of H₂ and 2 moles of O₂ are present then:
3 moles of H₂ would require 1.5 moles of O₂ ( 2 : 1 of H₂ and O₂ )
Out of 2 moles of O₂, 1.5 moles would be used and 0.5 mole would be in excess.
Therefore, H₂ is the limiting reactant as the number of moles of H₂ are not enough to use all the O₂.