Answer:
D. 1.2 cm
Explanation:
1st, determine the units. We see that our ruler is in cm.
This rules out A and C.
2nd, determine answer.
We see that the penny extends past 1 and ends at 0.2.
So, the total is 1.2 cm.
Great question, but I believe you are mixing up atomic number with mass number. Assuming you are, 12.011 amu is the average mass of a carbon atom. For carbon, it can come in three forms: carbon-12, carbon-13, carbon-14. The number following carbon is the mass number of that particular carbon "isotope". The reason the average is so close to 12 is because carbon-12 is by far the most common, so the average should be (and is) very close to 12. Therefore, 12.011 is a weighted average of all carbon molecules, and carbon-14 is a particular carbon molecule that weighs 14 amu.
Protons goes in the blank. the word can be used for both.
<u>Answer:</u> D. the ionic compound calcium fluoride 
The correct option here is the fourth one.
<u>Explanation:</u>
Salt like compounds addition to water is likely to be inducing certain changes in temperature of freezing into solid and also alter the temperature of boiling.
It is noticed that addition of salts in water mostly tends to get lower the freezing temperatures from the original freezing point of water and among the given 3 options calcium fluoride tends to lower the freezing point most when compared to others.
Thus as vant hoff factor is highest factor for
and the freezing point will be lowest.
Elements:
• atom
• cannot
• Periodic Table
Compounds:
• atoms
• chemically
• cannot
Mixtures:
• elements or compounds
• homogeneous
• heterogeneous