Problem: What is the name for the highly viscous layer of the earth that is about 2,890 km (1,800 miles) thick and makes up about 84 percent of Earth's volume?
Answer: mantle

Problem: In which decade did both Fridtjof Nansen and Frank Kellogg win the Nobel Peace prize
Answer: 1920s

Problem: What was the most used first name of the composer Mussorgsky (1839-1881).
Answer: modest

Problem: What colour is the cross on the national flag of Tonga?
Answer:
red