Which of the following combinations of particles represents an ion of net charge -1 and of mass number 82? group of answer choices:
a) 46 neutrons, 35 protons, 36 electrons
b) 46 neutrons, 36 protons, 35 electrons
c) 46 neutrons, 36 protons, 36 electrons
d) 47 neutrons, 35 protons, 35 electrons
e) 47 neutrons, 35 protons, 36 electrons

The correct choice is E (47 neutrons, 35 protons, 36 electrons)

Explanation:

A ion of net charge -1 means that the ion wins an e-.

We dismiss options B and C.

We also dismiss option A because neutrons + protons = 81.

neutrons + protons = mass number

So we have E and C.

We see that C has 47 neutrons, 36 protons and 36 electrons and, as the atomic number matches the number of protons, we find out on the Periodic Table that the atomic number 36 represents to Krypton, a noble gas. It is impossible! A noble gas never can't be a ion of net charge.

Option E is correct, It is an isotope of Br.

Br has 35 protons (its atomic number)

47 neutrons, that's why it is an Isotope (Br has always 45 neutrons)

As usual, Br has 35 electrons, if it represents a ion of net charge -1, it menas it won 1 e-.  

the answer is true. hope it .

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