I think it could be letter B
A human has 46 chromosomes which is 23 PAIRS
Answer: add up to eight
Explanation: NaO as one bond as it takes only one and seven to make eight. Leaving NaO with three lone pairs
1. Iron fillings are magnetic, so use a magnet to pull the iron fillings out of the mix.
2. Then you can put the salt and sand mixture into water, since salt is soluble, and the salt will dissolve, leaving you with sand.
4 x 1000 so 4 kilometers are equal to 4000 meters
