Its easier to reject the null hypothesis in a hypothesis

Question

True or False and justify

1. If all the observations in a data set are identical, then the variance for this data set is zero.
2. If A and B are disjoint, P(A) = 0.4 and P(B) = 0.5, then P(A AND B) = 0.2. 
3. The mean is always equal to the median for a normal distribution.
4. A 90% confidence interval is wider than a 95% confidence interval of the same parameter.
5. It's easier to reject the null hypothesis in a hypothesis test at 0.05 significance level than at 0.01 significance level.