Answer:
V₂ = 15.00 atm
Explanation:
Given data:
Initial pressure = 5.00 atm
Initial volume = 3.00 L
Final pressure = 760 mmHg ( 760/760 = 1 atm)
Final volume = ?
Solution:
P₁V₁ = P₂V₂
V₂ = P₁V₁ / P₂
V₂ = 5.00 atm × 3.00 L / 1 atm
V₂ = 15.00 atm
Answer : The final pressure will be, 666.2 mmHg
Explanation :
Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

or,

where,
= initial pressure = 790 mmHg
= final pressure = ?
= initial volume = 101.2 mL
= final volume = 120 mL
Now put all the given values in the above equation, we get:


Therefore, the final pressure will be, 666.2 mmHg
Molar mass NaCl = 58.44 g/mol
number of moles:
mass NaCl / molar mass
145 / 58.44 => 2.4811 moles of NaCl
Volume = 3.45 L
Therefore :
M = moles / volume in liters:
M = 2.4811 / 3.45
M = 0.719 mol/L⁻¹
hope this helps!