Q49 L1 and L3 are Context Free
L1 is ambnanbm ,here in one stack we will push first m a's then push n b's,then for each pop of 'b' print 'a' and each pop of 'a' print 'b', so only one stack is required, so CFL
L2 is ambnambn,, here two stacks will be required one stack will not be sufficient for comparison, say we have push first m a's then n b's in stack,then how to print m a's ? so 2 stacks will be required here.So not CFL
L1 is ambn,m=2n+1, is equivalent to a2n+1bn ,only one comparison so CFL