Answer:
(B) F⁻, HCOOH
Explanation:
(A) CH₄, HCOOH
(B) F⁻, HCOOH
(C) F⁻, CH₃-O-CH₃
The hydrogen bonds are formed when the hydrogen is found between two electronegative atoms such as oxygen (O), nitrogen (N) or florine (F).
O····H-O, F····H-O, O····H-N
(A) CH₄, HCOOH
- here methane CH₄ is not capable to form hydrogen bond with water
- formic acid HCOOH can form hydrogen bonds with water
H-C(=O)-O-H····OH₂
(B) F⁻, HCOOH
-both floride (F⁻) and formic acid can form hydrogen bonds with water
F····OH₂
H-C(=O)-O-H····OH₂
(C) F⁻, CH₃-O-CH₃
- dimethyl-ether CH₃-O-CH₃ is not capable to form hydrogen bond with water
- floride (F⁻) can form hydrogen bonds with water
F····OH₂
This problem is asking for the percent by mass of hydrogen in hydrofluoric acid. At the end, the answer turns out to be D. 5% as shown below:
<h3>Percent compositions:</h3>
In chemistry, percent compositions are used for us to know the relative amount of a specific element in a compound. In order to do so for hydrogen, we use the following formula, which can also be applied to any other element in a given compound:

Where
stands for the atomic mass of hydrogen and
for the molar mass of hydrofluoric acid. In such a way, we plug in the atomic masses of hydrogen (1.01 g/mol) and fluorine (19.0 g/mol) to obtain:

Learn more about percent compositions: brainly.com/question/12247957
Answer:
The answer is "The First choice".
Explanation:
The whole question can be found in the file attached.
The water vapor inside the air freezes thru the entrance of its nitrogen. This is because liquid nitrogen has a very low temperature and seems to be sufficiently cold to condensed and freeze the steam of water. At air pressure, it has a boiling temperature of -196°C. Freezing the skin producing freeze or cold burns can be associated with direct contact.
Ca=40
C=12
O=16
1 mole of CaCO3 has 100 grams
So 50 grams is 0.5 mole