Partition of Sample Space

Q. If events $E_1,E_2,...,E_n$ represent a partition of sample space S.
Then which of the following is/are correct?

1. $E_1\cap E_2=\varphi$
2. $E_1\cap E_2\ne \varphi$
3. $E_1\cup E_2\cup ...\cup E_n=S$
4. $P\left(E_i\right)>0\mathrm{for}\mathrm{all}i=1,2,\cdots ,n$

Q. A man is known to speak truth is 75% cases. If he throws an unbiased die and tells his friend that it is a six, then the probability that it is actually a six, is

1. $\frac{1}{6}$
2. $\frac{1}{8}$
3. $\frac{3}{4}$
   
4. $\frac{3}{8}$