1. It's 'World War Two' or 'the Second World War'. You don't need to say 'the World War Two'. It also depends on how you are using the word 'gothic'. If it is define a church as being built in the Gothic style (https://en.wikipedia.org/wiki/Gothic_architecture) then yes, it should be capitalised. If it is just looking gothic (ie, more of general style, rather than a specific architectural description) then it should be lower case. 2. I would amend the sentence as following: "The millionaire, whose son was kidnapped and rescued *safely*, donated ten million dollars to orphanages *across* the whole country". You need to use a word such as 'across/spread/throughout' to explain that they are throughout the country. 'In the whole country' isn't very clear. 3."The famous writer, whose books sold hundred million copies world-wide, gave a sumptuous party to celebrate her success." Using 'sold out' implies that there are no more books that she could sell. Saying that she sold 100 millions copies world wide doesn't imply this. If you wanted to say that her books are so popular that they sold out, you would need to say something like 'her books sold out bookshops world-wide'.