Answer:
b) The dehydrated sample absorbed moisture after heating
Explanation:
a) Strong initial heating caused some of the hydrate sample to splatter out.
This will result in a higher percent of water than the real one, because you assume in the calculation that the splattered sample was only water (which in not true).
b) The dehydrated sample absorbed moisture after heating.
Usually inorganic salts may absorbed moisture from the atmosphere so this will explain the 13% difference between calculated water percent the real content of water in the hydrate.
c) The amount of the hydrate sample used was too small.
It will create some errors but they do not create a difference of 13% difference as stated in the problem.
d) The crucible was not heated to constant mass before use.
Here the error is small.
e) Excess heating caused the dehydrated sample to decompose.
Usually the inorganic compounds are stable in the temperature range of this kind of experiments. If you have an organic compound which retain water molecules you may decompose the sample forming volatile compounds which will leave crucible so the error will be quite high.
Answer:
Dipole-dipole attractions
Explanation:
PBr₃ is a <em>trigonal pyramidal</em> molecule.
The P-Br bonds are polar, with their bond dipoles pointing toward the Br atoms (see below).
The x-components of the dipoles cancel, but the y-components reinforce each other.
The partially negative Br atoms are attracted to the partially positive N atoms in neighboring molecules.
These dipole-dipole forces are the strongest intermolecular forces in PBr₃.
<em>This statement is false.</em> When you say full octet, it means that an element opts to have eight electrons in its valence shell to become stable. However, since a hydrogen atom only has 1 electron when neutral, it is impossible to reach a full octet. That is why Hydrogen is one of the exceptions to this octet rule.
Benthos are "organisms inhabiting the seafloor" according to one source, so I would say the answer is C.