The diploid number for a lily whose pollen contains 12 chromosomes would be and is produced when the pollen, containing sperm, the egg. whats the blanks? ?

The answers would be 24 and fertilises. 

Pollen is the male gamete of lily, which is a haploid cell, with only half the chromosomes of the normal diploid ones. Therefore, if the haploid gamete has 12 chromosomes, so the diploid would be 12+12 which makes 24. 

The egg is also a gamete of lily, but it's a female gamete. It is also a haploid cell, with only 12 chromosomes which is given in the question. So, when the sperm fuses and fertilises the egg, the zygote would have 24 chromosomes which is formed by 2 haploid gametes. 

It would be 24 chromosomes. Diploid just means 2 so, you just multiply 12•2=24 (your diploid number). It is produced when the pollen containing sperm, fertilizes the egg.