75% nahi clear hua to ?

Yar Mera jee wagera to set hai april me improve bhi kar lunga jan attempt me 98.53 aye the (ik nothing to brag about) par theory bohot weak hai issiliye jee me chemestry me bas 55 aye abhi dar lag raha hai ki physics me cbse ne to mar hi li to approx 78-79 expect kar raha hu aur agar chem bhi hard aya aur 75 nahi hua to aggregate me dikkat ayegi. I heard people talking about compartment and improvement test and all and I don't know about them much so I have lots of doubt ki ye compartment aur improvement test me kaya difference hai aur kon kon de sakte hai aur ye kab hote hai ? Any idea anyone ?