What weathering breaks things down but keeps the same substance?

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks

How has the geography of india made it difficult for its people to expand before modern technology?

Which barrier to economic development is shown in the following examples?