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 .
Answer:
Buffers are resistant to high pH changes.
Explanation:
This perfectly explains the reason why we use buffers. Buffers are substances which consist of a weak acid and its conjugate base. Buffers are resistant to significant pH changes upon addition of strong acids or bases. To illustrate this, let's say we have a buffer consisting of 0.1 mol of HF, a weak acid, and 0.1 mol of NaF (fluoride is a conjugate base of HF).
- Let's say we add some strong acid, in a general form, this acid would be represented as
. In this case, conjugate base will react and neutralize it to produce some amount of HF: 
. - Similarly, if we add some strong base
, the acidic component will react with it to produce some amount of conjugate base: 
. The ratio of HF to NaF in this case is held around the same value for addition of small amounts of strong acids/bases, so pH is kept almost constant, while in neutral water, pH would drastically increase or decrease.
Answer:
Explanation: Well each branch has its own little job especially when it comes to society. First we have the Organic Chemistry Branch It includes the study of all the possible compounds which have carbon in them. Then we have the Inorganic Chemistry Branch, the inorganic compounds find their use in medicine, food, agriculture and also technology. Next we have the Biochemistry Branch it deals with chemistry happening inside the living bodies of animals and plants. This subject is huge and plays an important role in medicine, agriculture, poultry, fisheries, etc. And finally we have the Physical Chemistry Branch it deals with the physical properties of chemicals or substances. It includes topics like gaseous laws (Dalton law), thermal conduction in liquids, gases, solids. The conductivity of electrolytes (used in batteries) liquids etc. It also deals with processes like sublimation, melting point, boiling point, the crystal structure of compounds, etc.
Using the combined gas law, where PV/T = constant, we first solve for PV/T for the initial conditions: (4.50 atm)(36.0 mL)/(10.0 + 273.15 K) = 0.57213.
Remember to use absolute temperature.
For the final conditions: (3.50 atm)(85.0 mL)/T = 297.5/T
Since these must equal, 0.57213 = 297.5/T
T = 519.98 K
Subtracting 273.15 gives 246.83 degC.
