sir I am in class 10 and I have got only 15 marks out of 60 in nso Olympiad so can I get selected in aiims mbbs

dear jahnavi 
donot worry , NSO is just to check your understanding level . 
and frst of all try to clear your besics for aiims , that u have to do in class 10^th itself , else , once u moved to class 11^th , then u have to start serious preparation for aiims , so, u will not get time to clear the besics at that time , 
so, do that now , and as of now , no need to worry about aiims , start prep from class 11^th onwards . 
ALL THE BEST 
REGARDS