Science and Nature Quiz for 22 January 2014

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Question 1: The fifteen elements with atomic numbers 57 to 71, which includes Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Europium (Eu), Erbium (Er), Thulium (Tm), Ytterbium (Yb) and Lutetium (Lu), are known as what?