If the pollen grain of a plant has 40 pg of DNA in its nucleus then how much DNA would a diploid cell of the same organism have in metaphase-I of meiosis ?

The amount of DNA in pollen grain is C- haploid (40 pg)

A diploid cell has 2c  (80 pg)amount of DNA. But prior entering the meiosis -I, during interphase (S phase) the amount of DNA doubles. Therefore, the amount of DNA becomes( 160pg) . At the end of meiosis four daughter cells are forming . 160 pg  of DNA is equally distributing to all four daughter cells. Each daughter cell receives 40 pg.