The $pH$ value of human urine is:

The following figure shows a longitudinal section of the kidney. Which part represents the renal column?

In humans,the primary excretory system consists of:
$I.$ Pair of kidneys
$II.$ One pair of ureters
$III.$ Urinary bladder
$IV.$ Urethra
$V.$ Skin
$VI.$ Lungs
$VII.$ Liver

Identify the correct statements:
$I.$ The outer layer of the kidney is called a capsule.
$II.$ The kidney is divided into an outer cortex and an inner medulla.
$III.$ The medulla is divided into medullary pyramids.
$IV.$ The cortex extends in between the medullary pyramids,which is called the columns of Bertini.
Choose the correct option accordingly.

Provide definitions/explanations for the following terms:
$(1)$ Column of Bertini
$(2)$ Excretory unit (nephron)

Malpighian corpuscles are found in the ........ .