Contact angle is a simple and effective technique for measuring whether a solution will readily wet a pressed powder (or drug). Which of the following is correct?

Select one:

a.

The contact angle greater than 140^o is perfect for making pharmaceutical drugs as superhydrophobic surfaces are the most desired

b.

The contact angle should be at least 90 and less than 140 for penetration into the solid to occur

c.

A contact angle value of below 90 is optimal to ensure a fast wetting and an easily prepared suspension

d.

Contact angle measurements are difficult and only can be taken by an expert with years of training