Answer:
Is this math? Cause as a fourth grader, I can do Algebra, but not this.
Explanation:
Potassium is not found free in nature but is found in the form of potash. Potash is the ore of potassium and this ore is mined from deep down the earth or can sometimes be found on the surface. Potash was mostly formed as sea water receded and left deposits.
Potash is usually in the form of potassium salts such potassium chloride and potassium sulphate. The potash is mined then taken to the factory where it is crushed and purified by removing such impurities as clay.
The now purified potassium salts are subjected to a process called electrolysis where potassium metal is obtained from its salt.
Ca(s)+2Hcl(aq) ------>CaCl2(s)+H2(g)
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 .
