Which part of the nephron is involved in the active reabsorption of sodium?

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.

Name two actively transported substances in glomerular filtrate.

$A$ large quantity of fluid is filtered every day by the nephrons in the kidneys. Only about $1\%$ of it is excreted as urine. The remaining $99\%$ of the filtrate

The urine of man under normal conditions does not contain glucose because:

Which substances are secreted in the $DCT$?