There are many forms of VIF and each forms are made for different purposes. basically, you just extract a female egg and a sample of the male sperm, bad sperm can be separated via by adding specific chemicals. The sperm will then be transferred into the egg and the egg is transferred into the women. (This is ICSI) There are other forms under the category of IVF but this is one of the example. (ICSI only deals with male infertility)
Nitrogen-14 has a mass number of 14 which means that it has a total of 14 protons and neutrons. When you subtract the atomic number of nitrogen from the mass number of 14 you get the number of neutrons (14-7), which gives you 7 neutrons. Now for nitrogen-15, you have a different mass number which means there is a different amount of neutrons (15-7), 8 neutrons. So the difference is the mass numbers and the number of neutrons (the number of protons remains the same however). When there are two versions of the same element, and they have the same number of protons, but different number of neutrons and different mass numbers, they are called isotopes. Hope this helped :)
Friction causes moving objects to slow down or stop.
