Read the following passage and answer the questions that follow. the second amendment to the u. s. constitution, which is a frequent source of controversy in public debates, says that "a well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed." the controversy stems from the fact that some americans feel that the second amendment guarantees all citizens the absolute right to own firearms, while others believe that some restrictions on gun ownership are consistent with the second amendment. which phrase from this passage demonstrates that the author is identifying a source of debate?

When the author states "which is a frequent source of controversy in public debates," he is giving us some indication that the information that follows is a source of debate. The debate is that people cannot always agree on what the exact meaning of the amendment is.

question - in 1827, john walker, a druggist in a small english town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. the druggist had discovered the first friction-chemical match, the kind we use to-day. it is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. although walker's match did not require the bottle of acid, nevertheless it was not a good one. it could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. in a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. the match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. it would ignite when rubbed on any dry surface, and there was no longer any sputtering. this was the phosphorus match, the match with which we are so familiar. according the paragraph what was the benefit of the new phosphorus match? it burst into flame when rubbed on sandpaper. it was made by mixing chemicals. it could be ignited on any dry surface. it threw fire in all directions.

answer - matches required natural chemicals