The answer is false because a building is heavier
Iron rusts when exposed to air → chemical property
Half life is the time that it takes for half of the original value of some amount of a radioactive element to decay.
We have the following equation representing the half-life decay:

A is the resulting amount after t time
Ao is the initial amount = 50 mg
t= Elapsed time
t half is the half-life of the substance = 14.3 days
We replace the know values into the equation to have an exponential decay function for a 50mg sample

That would be the answer for a)
To know the P-32 remaining after 84 days we have to replace this value in the equation:

So, after 84 days the P-32 remaining will be 0.85 mg
Answer:
Sulphur
Explanation:
Sulphur(S) is the Sixteenth element of the periodic table and it has an electronic configuration of 2,8,6. This means it has six electrons in its outermost shell( valence electrons).
Sulphur has sixteen(16) protons which is equal to the atomic number which is also sixteen. Sulphur ends with the letter ‘r’. All the descriptions of the element are satisfied and it validates Sulphur.
Answer: Option D) covalent bonds between water molecules
In water, hydrogen bonds are best described as covalent bonds between water molecules
Explanation:
The hydrogen bonds between water molecules are covalent bonds because they are formed when oxygen attract the lone electron in hydrogen, thus resulting in the formation of a partially negative charge on the oxygen atom and a partially positive charge on two hydrogen atoms
Thus, the sharing of electrons between oxygen and hydrogen atoms is responsible for the covalent bonds between water molecules