In diploid organisms, having two homologues of each chromosome can be beneficial if one allele of a gene encodes a nonfunctional protein. can haploid organisms avoid the negative effects of nonfunctional alleles?

No , they can't avoid
hope helped

I think that the haploid organisms can NOT avoid the negative effects of nonfunctional alleles. This is because there is only one allele for the gene in each cell, and therefore the nonfunctional allele has no other allele to mask it. Haploid cells are those cells that contain only a single number of alleles (n) unlike diploid cells which contain a pair of alleles (2n).