In $ECG,$ $T$-wave represents:

Complete the missing words in the statements given below:
$(a)$ Plasma without clotting factors is called serum.
$(b)$ $.........$ and monocytes are phagocytic cells.
$(c)$ Eosinophils are associated with $.........$ reactions.
$(d)$ $.........$ ions play a significant role in clotting.
$(e)$ One can determine the heart beat rate by counting the number of $.........$ in an $ECG$.

The diagram given here is the standard $ECG$ of a normal person. The $P-$ wave represents the:

Which of the following is a repolarization wave?

Given below are two statements.
Statement $I$ - Graphical recording of electrical variations detected at the surface of body during their propagation through the wall of heart is electrocardiograph.
Statement $II$ - The instrument used for the graphical recording of electrical variations detected at the surface of body during their propagation through wall of heart is electrocardiogram.
In the light of above statements,select the correct option given below:

The figure below shows a typical $ECG$ of a normal human. What does the $P$-wave represent?