Theory of Computation: Context-Free Grammar, Parsing Tree

Please show all steps of your working and give explanations as I am not understanding these at all. Thanks in advance.

2. [12 marks] Give context-free grammars that generate the following languages. (a) The language (wE 0,* the length of w is odd and the middle symbol is 0) (b) The language (a bi cki,j, k 20, and i -j or i-k (c) The language a"bm | m Sn S2m (d) 0. , and l j or i k 3. [3 marks] Draw the parse tree of the string 100101 for the CFG you provided in question 2a. Is the CFG ambiguous