Here's why:

* Milliliters (ml) measure volume, which is the amount of space a substance occupies.

* Pounds (lbs) measure weight, which is the force of gravity acting on a mass.

To convert between volume and weight, you need to know the density of the substance. Density is the mass per unit volume.

For example:

* Water: 1 ml of water weighs approximately 1 gram.

* Oil: 1 ml of oil weighs less than 1 gram.

Therefore, to convert 30 ml to pounds, you need to know the substance you're measuring.

Let me know if you can provide the substance, and I can help you with the conversion!