Glucose and $80\%$ of water are reabsorbed in which part of the nephron?

The lining of the proximal convoluted tubule $(PCT)$ is made up of $.......$.

Which of the following statements is correct regarding the reabsorption of $K^+$ (Potassium) in the nephron?

Given below are two statements:
Statement $I$: In the nephron,the descending limb of the loop of Henle is impermeable to water and permeable to electrolytes.
Statement $II$: The proximal convoluted tubule is lined by simple columnar brush border epithelium and increases the surface area for reabsorption.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following statement$(s)$ is/are true?
$(1)$ Urine is hypertonic in the distal convoluted tubule.
$(2)$ When the urine passes into the collecting tubule,it becomes hypotonic.
$(3)$ Urine is isotonic in the proximal convoluted tubule.
$(4)$ Urine becomes more and more hypotonic as it passes through Henle's loop.

Reabsorption of useful substances back into the blood from the filtrate in a nephron occurs in