The slight error has been to use the prefix mono to name monocarbon.The compound she is most likely naming is:

.
As you see, the chemical formula has 1 atom of C, which is likely why she named it mono, and 4 atoms of Br.
The right name is carbon monobromide, i.e. you have to supress the prefix mono, as per IUPAC rules.
Answer:
Six
Explanation:
Oxygen has six valence electrons in its elemental form so its formal charge is 6 – 6 = 0. Each hydrogen atom owns one electron [(2x½) = 1].
Answer:
55 degrees F - cold water
120 degrees F
the last on I don't know
Answer:

Explanation:
Hello,
In this case, for such formation of sulfur hexafluoride, the standard enthalpy of formation is -1220.47 kJ/mol (data extracted from NIST database). Next, we compute the moles in 10.0 grams of sulfur hexafluoride as shown below:

Next, for the given energy, we compute the total heat that is liberated:

Finally, we conclude such symbol has sense since negative heat is related with liberated heat.
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