In this item, it is assumed that we are to express the given compound in their ionic form. To be able to determine as to what ions this compound will dissociate into, we have the chemical reaction.
HNO3 --> H⁺ + NO₃⁻
Hence, the ions are H⁺, NO₃⁻.
The substance that can be classified as being soluble in water would be salt. The solution is D. Salt specifically is composed of ions and the ionic compound dissociates within water.
It's called simple diffusion, the small molecules without charges such as oxygen and carbon dioxide can flow through a plasma membrane without assistance and without expending energy. Other substances such as proteins, glucose and charged particles called ions cannot pass through the selectively permeable membrane.
