The precise definition of these should be in your text book. In simple (and therefore approximate) language:Give the null and the alternative hypotheses.
Null hyopthesis: This is the "baseline" that you are going to compare to. the purpose of the test is to see if there is there is a significant deviation from the expected "baseline" result. If there is a significant deviation, you conclude that the null hypothesis was false.
eg: Null: Population mean is 10
Alternative Hypothesis: If the null hypothesis isn't true, then some "alternative" hypothesis must be correct. In a statistical test, the alternative hypothesis specifies the type of deviation from the baseline that you want to test for. This is necessary for technical reasons to decide whether a deviation is significant or not.
eg: Alternative: Population mean > 10
If i give you the following information, what do you think the "baseline" and "expected deviation" might be? hints in bold.
A producer of various kinds of batteries has been producing "D" size batteries with a life
expectancy of 87 hours. Due to an improved production process, management believes that there has
been an increase in the life expectancy
Your issue with the second question seems to be similar. Post your attempt for the rest and say where you are stuck if you need more help.