Explanation:
So the gas pressure of a helium balloon arises from the impact of the collisions of the helium atoms between themselves and with the inside surface of the balloon. Of course, the outside atmosphere similarly exerts a pressure on the outside of the balloon.
Answer:
1. 
2. 
Explanation:
An ion is formed when an atom that is said to be neutral gains or losses electrons.
It is thought that a negative ion (anion) is produced as it gains electrons and a positive ion (cation) is formed when it loses an electron.
Atomic number is the total number of protons and electrons in a neutral atom.
From the information
Protons = 14
electron = 18
Net Charge = no of proton - no of electron
= 14 - 18 = -4
Mass number = 14 + 15 = 29
Thus, the chemical symbol = 
For ion with 27 proton, 32 neutrons and 25 electrons
Net charge = 27 - 25 = +2
Mass number = 27 + 32 = 59
Thus, the chemical symbol = 
Answer:
1.7 * 10^-5
Explanation:
1- get the number of moles of PbCl2:
number of moles = mass / molar mass
number of moles = 0.45 / 278.1 = 1.618 * 10^-3 moles
2- get the concentration of Pb2+:
molarity = number of moles of solute / volume of solution in liters
molarity = (1.618 * 10^-3) / (0.1) = 0.0162 M
3- getting concentration of Cl-:
<span>PbCl2(s) <==> Pb2+(aq) + 2Cl-(aq)
</span>We can note that:
For a certain amount of Pb2+ formed, twice this amount of Cl- is formed.
This means that:
for 0.0162 M of Pb2+, 2*0.0168 = 0.0324 M of Cl- is formed
4- getting Ksp:
Ksp = [Pb2+][Cl-]²
Ksp = (0.0162)*(0.0324)²
Ksp = 1.7 * 10^-5
Hope this helps :)