Which of the following is a monatomic cation?

a. fr+ < -- i believe this is correct.

b. nh4+

c. br-

d. oh-

A. Fr+

Explanation:

A monatomic ion is an ion consisting of exactly one atom. If an ion contains more than one atom, even if these are of the same element, it is called a polyatomic ion. For example, calcium carbonate consists of the monatomic ion Ca²⁺ and the polyatomic ion CO₃²⁻.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.