Under the Highway Traffic Act, children must use a forward-facing child car seat when they weigh between 9 kg and 18 kg (20 to 40 lb.) You need to use a forward-facing child car seat until your child weighs at least 18 kilograms (40 lb.). This is a minimum requirement.
only one sperm can enter an egg (first come first serve) only one egg can be fertilized at a time Answer Actually 2 or more can but the baby won't make it to birth. My daughter died at 16 weeks. I had the baby tested and she had been fertilized by 2 sperms. I agree with this answer.
A process called meiosis makes sure that when a gamete is made, the sperm or the egg cell each only has 23 chromosomes, half of the original number, so that when they join to form a zygote when fertilization occurs, the zygote will have a total of 46 chromosomes, like every cell in a human does. So the answer is 23.