Logic Riddles

Question: In the middle of winter, a woman is found dead in her bed, with multiple stab wounds in the stomach. Soaked into the sheets is a massive amount of blood, along with blood drops on the carpet. On the side table beside her bed, there is a glass full of water mixed with blood. What was the murder weapon, where is it now, and how was she killed?

Question: The 22nd and 24th Presidents had the same biological mother and father, but weren't brothers. They were both male, and were never female. Neither were adopted or "switched at birth". How is this possible?

Question: what is small but can save things that do not weight anything in it?

Question: If 1+1=4, 7-3=2, and 5x2=8, then what is half of 19?

Question: What goes next: 4,7,93,12,9,8,?