What causes the shielding effect to remain constant across a period?

This is because the number of orbital shells does not increase. The non-valence orbitals remain the same with maximum electron configuration; with only the valence orbital changing. Therefore the valence orbital is shielded the same, by the non-changing lower orbital levels, from the attraction force of the atomic nucleus.

d. in sexual reproduction, offspring have more chromosomes than

either parent.

asexual reproduction results in offspring which are genetically the same as the parent organism (not counting a rare mutation). sexual reproduction produces a random mixture of the genetics derived from both parents

explanation:

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