Which is most likely to form a negative ion?

A. An element from group 17

B. A metal

C. An element from group 1

D. An element with atoms that have eight valence electrons

A

Explanation:

In other options, they form positive ion as they have extra electrons in their valence shell

But in group 17, all the elements have 7 electrons in their valence shell,inorder to attain octet they require one more electron

Hence,they form negative ion by gaining electron

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.