Answer:(4) ----accepts a proton
Explanation:
H2O water can produce both hydrogen and hydroxide ions
H2O --> H+ + OH-
According to the Bronsted-Lowry theory, it can be a proton donor and a proton acceptor.this means that It can donate a hydrogen ion to become its conjugate base, or can accept a hydrogen ion to form its conjugate acid,
When , a water molecule, H2O accepts a proton it will act as a Brønsted-Lowry base especially when dissolved in a strong acidic medium. for eg
HCl + H2O(l) → H3O+(aq) + Cl−(aq)
Here, Hydrochloric acid is a strong acid and ionizes completely in water, since it is more acidic than water, the water will act as a base.
Answer:
c tarnishes in air
Explanation:
After silver has been exposed to air that contains sulphur gases, discoloration would occur. there would be darkening that is caused by the reaction with gases.When any silver object tarnishes, it brings about a disfiguring of that object. Hydrogen sulphide would be needed for this to happen. silver sulphide is black and a if a thin layer should form on any surface, it ill darken it. This is what we refer to as tarnishing.
Answer:
A. 
B. 
Explanation:
Hello!
In this case, since the undergoing chemical reaction between nitrogen and hydrogen is:

Thus we proceed as follows:
A. Here, we first need to compute the moles of ammonia yielded by each reactant, in order to identify the limiting one:

Thus, since nitrogen yields the fewest moles of ammonia, we realize it is the limiting reactant, so the theoretical yield, in grams, of ammonia is:

B. Finally, since the actual yield of ammonia is 1.23, the percent yield turns out:

Best regards!
Mole ratio for the reaction is 1:1
no of moles in NaOH that reacted= 1*21.17/1000=0.02117mols
molarity of HCl=0.02117*10/1000
=2.117M
Answer:
the answer is 18 atoms [your welcome]