Isolated atom basically means atom which exists separatly without any bonding with other atoms. It can only be acheived experimentaly because normally all atoms are bonded together by strong nuclear forces and its really hard to isolate a single atom.
Step 
<u>find the mass of a single washer</u>
Divide the total mass by the number of washers


Step 
<u>Convert kg to mg</u>
we know that

so

therefore
<u>the answer is</u>

Answer:
This question is incomplete.
Explanation:
This question is incomplete because of the absence of given mass and volume, however, the steps below will help solve the completed question. The molarity (M) of a solution is the number of moles of solute per liter of solvent. The formula is illustrated below;
Molarity = number of moles (n) / volume (in liter or dm³)
To calculate the number of moles of NaC₂H₃O₂, we say
number of moles (n) =
given or measured mass of NaC₂H₃O₂ ÷ molar mass of NaC₂H₃O₂
The volume of the solvent must be in liter (same as dm³). Thus, to convert mL to liter, we divide by 1000
The unit for Molarity is M (Molar concentration), mol/L or mol/dm³
Answer: the correct option is A (A zero net force causes no change to an object's
motion.)
Explanation:
Force is a vector quantity that causes an object to accelerate or change velocity when pushed or pulled. While a NET FORCE can be defined as the combination of all forces acting on an object which is equally capable of accelerating the object.
When a NET FORCE is equal to zero( that is zero net force),there will be no change to an object's motion. When the net force of an object is equal to zero , it shows the object is in either static equilibrium( the objects velocity is zero) or dynamic equilibrium(where the object is moving at constant velocity). In both cases, the object remains motionless because the net forces is equal to zero.