Why are black holes so difficult to detect?

Black holes are so dense that light cannot escape from them, and they are difficult to detect. Satellites above the Earth's atmosphere can detect bursts of high energy radiation given off by black holes. Dozens of stellar black holes have already been detected in the Milky Way, where there may be tens of millions more.

Explanation:

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.