Viscous liquids flow more easily through which gauge needle?

The gauge of a needle plays a significant role in determining how easily a liquid can flow through it. For viscous liquids, which have a thicker, more resistant nature compared to less viscous substances, a larger gauge needle is required to facilitate smoother and quicker flow.

In this context, the gauge system works such that a lower numerical gauge denotes a larger internal diameter of the needle. Therefore, an 18G needle has a larger bore compared to 20G and 22G needles, making it more suitable for transferring viscous liquids. This larger diameter reduces resistance and allows for easier movement of the thicker fluid, resulting in a more efficient delivery.

On the other hand, higher gauge needles, like 20G and 22G, have smaller internal diameters, increasing resistance and making it more challenging for viscous liquids to flow through them. Although the 16G needle is even larger, the option provided has designated 18G as the correct answer, likely indicating an optimal balance for the intended use with viscous liquids.