Cobalt (Co) has an atomic mass of 59 and an atomic number of 27. Which statement correctly describes an atom of cobalt? A. An atom of cobalt contains more neutrons than protons.
B. An atom of cobalt contains more electrons than protons.
C. An atom of cobalt contains the same number of neutrons and protons.
D. An atom of cobalt contains the same number of neutrons, electrons and protons.

A

Explanation:

27 us the number of protons when we subtract 27 from 59 it will be 32 because a mass number is the sum of proton and neutron but tell u more on the comment

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