pV = nRT
p = nRT/V
p= 1 x 0.08205 x 1000/ 2
p = 41.025 Pa
Edit: The unit should be atm instead of Pa, as pointed out by a nice human being.
The molecular weight of hemoglobin can be calculated using osmotic pressure
Osmotic pressure is a colligative property and it depends on molarity as
πV = nRT
where
π = osmotic pressure
V = volume = 1mL = 0.001 L
n = moles
R = gas constant = 0.0821 L atm / mol K
T = temperature = 25°C = 25 + 273 K = 298 K
Putting values we will get value of moles

we know that

Therefore

Answer:
Depends, but in most cases, 2.
It's best to use as many digits as possible to keep it accurate.
Explanation:
This varies between teachers, as most schools go with 2 decimal places.
This is something that depends in your situation.
You technically want as many decimals as possible to keep it as accurate, but most people stick with 2.
I personally do 3, and commonly do 5 sometimes.