What is the bronsted-lowry definition of an acid?

a compound that donates protons

a compound that accepts protons

a substance that increases hydroxide ion concentration

a substance that increases hydronium ion concentration

The correct answer is that a compound that donates protons.  

On the basis of Bronsted-Lowry concept, a compound which accepts proton is considered as a base and the compound which donates protons is considered to be an acid. The strong acids and bases get ionized completely in aqueous solution, while the weak acids and weak bases get ionize partially.  

The conjugate base is illustrated as the species that is produced after the loss of proton of acid, while the conjugate acid refers to the species that is produced after the gain of protons.  

Thus, the Bronsted-Lowry definition of an acid is a compound that donates protons.  

Option A: a compound that donates protons

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.

the answer is c

tell me if wrong