In a heterozygote cross (aa x aa) what is the probability of producing offspring that exhibit the dominant phenotype for this trait?

Let 'A' denote the dominant allele and 'a' denote the recessive allele. The heterozygous cross will involve a cross between Aa and Aa i.e, Aa x Aa. The image shows the cross using a Punnett square to give an idea about the resultant offspring genotypes. The resultant offspring will have 3 dominant phenotype (yellow colored) and 1 recessive phenotype. Thus the probability of the dominant phenotype in the offspring is 75% or 3/4.

a covalent bond, specfically triple bond