Misc: what gooey, bouncy, stretchy substance is sold in an "egg"?

Questions

1970s Hits: This brother act had 4 #1's in 1970...?

1970s Hits: This group song the 1978 #1 "Baby Come Back"?

1970s Hits: This instrumentalist hit #1 in 1977 with the theme from "Star Wars"?

1970s Hits: This singer was the first to have his first 3 singles hit #1?

1971 Num1 Hits: "Gypsies, Tramps, and Thieves" was #1 for how many weeks?