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.
Humans have 46 chromosomes in each cell. During fertilization of the egg, the sperm nucleus containing 23 chromosomes from the paternal side fuses with the nucleus of the egg that contains 23 chromosomes from the maternal side. The result is the zygote that contains 46 chromosomes (23 pairs of chromosomes; one of each pair from either parent).