Identifying the difference between ‘False’ and ‘Not given’ can sometimes be complicated, but a basic rule you can apply is this – are the 2 things both possible, or is only one possible?
To illustrate with a very simple example, if the text said ‘the sun is hot’ and the T/F/NG statement was ‘The sun is yellow’, you need to decide whether it is possible for something to be hot and yellow. In this case, the answer would be not given, because both are possible (they are not mutually exclusive).
However, if the statement was ‘The sun is cold’ then the answer is false because the it cannot be both hot and cold at the same time, therefore the answer is false.
Another useful rule of thumb is that if an answer is ‘false’ then you must be able to show specific evidence to support that, something that contradicts the statement. If you can find no evidence to contradict the statement, it’s ‘Not given’.