The blotting paper helps observe liquid by ____?

The blotting paper helps observe liquid by ____?

بلوٹنگ پیپر ____ کے ذریعے مائع کا مشاہدہ کرنے میں مدد کرتا ہے؟
Explanation

Capillary action is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces like gravity.