What affect does salt have on ice

Before the civil war, the constitution protected slavery -true -false

The irish and germans of the 1840's were part of the new immigration. true or false

The rise of advertising in the 1920s. i am good with seeing how advertisements shape the roaring twenties and how it developed a new way of life through modern days. but i am not sure what the details of advertising in the 1920s were. if possible can you send me links (preferrably credential links) to sources that maybe show like the first company to start advertising through the radio, how advertising benefits (statistics graphs), etc.