Problem: What does the Mohs scale measure?
Answer: hardness of minerals

Problem: "Historian Richard B. Morris, in his book ""Seven Who Shaped Our Destiny"" (1973), identified Benjamin Franklin, George Washington, John Adams, Thomas Jefferson, John Jay, James Madison, and Alexander Hamilton as the key what?"
Answer: founding fathers

Problem: The Five Sisters of 'where' appear in a story told in the novel 'Nicholas Nickleby' by Charles Dickens?
Answer: york

Problem: Which Irish folk band had UK 'top twenty' hits in 1967 with 'Seven Drunken Nights' and 'Black Velvet Band'?
Answer:
dubliners