UnScramble this Word: i n e q i g u t?

Questions

during the cambrian period, about 500 million years ago, a day was only ---------- hours long?

during the---------- , banks first used scotch tape to mend torn currency?

during the depression, ---------- first used scotch tape to mend torn currency?

during the depression, banks first used ---------- tape to mend torn currency?

during the ---------- century, books that were considered offensive were sometimes punished by being whipped?