If i have two atoms, atom a has 34 protons, 45 neutrons, and 34 electrons, atom b has 35 protons, 45 neutrons, 35electrons. what best describes the two atoms

The atomic symbol of an element is given as:

where X is symbol of the element, Z is the atomic number and A is the mass number of the element.

The number of protons present in an atom is the identity of the number of element which is equal to the atomic number of the element, which is unique for every element.

The sum of number of neutrons and protons in an atom is mass number of that atom.

The given information for Atom A is:

34 protons

45 neutrons

34 electrons

Since, number of protons = atomic number. So, atomic number of Atom A is 34. The element with atomic number 34 is selenium, .

The number of protons and electrons is same i.e. 34 for an atom thus, the atom A is a neutral atom.

The mass number = number of protons + number of neutrons

Mass number of atom A =

Thus, atom A is .

The given information for Atom B is:

35 protons

45 neutrons

35 electrons

Since, number of protons = atomic number. So, atomic number of Atom B is 35. The element with atomic number 35 is bromine, .

The mass number = number of protons + number of neutrons

Mass number of atom B =

The number of protons and electrons is same i.e. 35 for an atom thus, the atom B is a neutral atom.

Thus, atom B is .

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol