You have two cups one is 6cm and other 10cm with no measurement and you have to pour 8cm of water into the 10cm cup using the two cup, without measuring it. how can you?

Here’s one way to do it.

1. Fill the 6 cm cup.

2. Pour its contents into the 10 cm cup. This leaves 4 cm yet to be filled.

3. Refill the 6 cm cup and use it to fill the 10 cm cup. This leaves 2 cm in the 6 cm cup.

4. Empty the 10 cm cup and add the 2 cm from the 6 cm cup.

5. Refill the 6 cm cup.

6. Pour its contents into the 10 cm cup.

The 10 cm cup now contains 8 cm of water.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.