Who discovered the $Rh$ factor?

Which of the following components, if introduced into the bloodstream, will cause blood clotting at the site of introduction?

What is the percentage of hemoglobin in $RBCs$ (in $\%$)?

If you are to collect blood from a patient and store it in a test tube for the separation of blood cells and plasma,which of the following test tubes would you $NOT$ use?

Choose the correct statement from the following.

Which is the primary cation present in the blood plasma?