I believe the correct answer is option B. Molarity is the <span>number of moles of solute that is dissolved in 1 liter of solution. It is another way of expressing concentration of a mixture especially for solutions. Percent by mass is grams solute per grams of solution. Percent by volume is liter solute per liter per solution.</span>
Answer:- 
molecules.
Solution:- The grams of tetrabromomethane are given and it asks to calculate the number of molecules.
It is a two step unit conversion problem. In the first step, grams are converted to moles on dividing the grams by molar mass.
In second step, the moles are converted to molecules on multiplying by Avogadro number.
Molar mass of 
= 12+4(79.9) = 331.6 g per mol
let's make the set up using dimensional analysis:
= molecules
So, there will be molecules in 250 grams of .
*A & B*
Answers A & B are not possible, as Hydrogen “bonds” are intermolecular forces and do not actually involve transfer or sharing of electrons.
*C & D*
Viscosity and surface tension are not the answer as they are not specific enough to the question.
*E*
Polarity of water molecules is the correct answer, as water molecules are highly polar. The partial positive of the Hydrogen on one water molecule is highly attracted to the partial negative of the Oxygen (due to its lone pairs) on another water molecule.
Water molecules are made of hydrogen atoms and one oxygen atom.
Hope this helped!
One of the differences I can think of is that hydrogen is no longer listed as a group I element.
According to the mendeleev tables that I looked up, hydrogen is catorgrized as a group I element, along with Lithium, sodium, Potassium etc. However, nowadays, hydrogen does not belong to any groups in the periodic table. This is because there are arguments about whether hydrogen belongs to group I. Group I elements are all alkali metals, while hydrogen is not. However, some people says that hydrogen only have one outer shell electron so it should be in group I. Some people even say hydrogen should belong to group VII because it only needs one more electron in order to achieve the duplet of electrons.
Therefore as you may notice, hydrogen in modern periodic tables are put in the center of the periodic table on the top.
