Questions

Covalent bonds are bonds formed between two non metals by sharing of electrons in their outer most orbits for stable.

The average Life span of RBC is 120 days.

Troposphere is the most densest layer and is the lowest atmospheric layer.

The plant cell organelles, "The power house of the cell" mitochondria and the chloroplasts contains their own DNA and ribosomes.

The sentence talks about “drought and food security” which has pestered the region and in addition to that the climate and geography has worsened the matter and forced them to come to isolation. “Relegate and downgrade” are the two words which means to move down to a lower position arethe most suitable word to be filled in the blank. “alleviates” which means to make less severe, will not complete the sentence sensibly. “Transgress” which means “to misbehave or to break the law” which does not fit in the context whatsoever.