Gold has a heavy enough nucleus that its electrons must travel at speeds nearing the speed of light to prevent them from falling into the nucleus. This relativistic effect applies to those orbitals that have appreciable density at the nucleus, such as s and p orbitals. These relativistic electrons gain mass and as a consequence, their orbits contract. As these s and (to some degree) p orbits are contracted, the other electrons in d and f orbitals are better screened from the nucleus and their orbitals actually expand.
Since the 6s orbital with one electron is contracted, this electron is more tightly bound to the nucleus and less available for bonding with other atoms. The 4f and 5d orbitals expand, but can't be involved in bond formation since they are completely filled. This is why gold is relatively unreactive.
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Answer:
The correct option is C
Explanation:
From the question we are told that
The reaction is
Generally 
Here 
is the change in enthalpy
is the change in the internal energy
is the difference between that number of moles of product and the number of moles of reactant
Looking at the reaction we can discover that the elements that was consumed and the element that was formed is 
and 
and this are both gases so the change would occur in the number of moles
So
![\Delta H = \Delta U + [16 -23]* RT](https://tex.z-dn.net/?f=%5CDelta%20%20H%20%20%3D%20%20%5CDelta%20%20U%20%2B%20%5B16%20-23%5D%2A%20%20RT)
The negative sign in the equation tell us that the enthalpy
would be less than the Internal energy 
It is called rust and it forms when water soaks into the metal forming a chemical reaction.
Answer:
D. Ash is a different substance than wood.
