PRELIMINARY STAGE 2025
Contest 15
Fijai SHS: 37 points (Winner, qualified to the one-eighth stage)
Nsutaman Catholic SHS: 36 points
Oda SHS: 26 points
QUESTION
Name one element with atomic number greater than 10 and whose symbol begins with the letter H.
ANSWER: Mercury (Hg), Hassium (Hs), Hafnium (Hf), or Holmium (Ho)
SOLUTION:
Several elements beyond atomic number 10 have symbols starting with H: mercury (Hg, 80), hafnium (Hf, 72), holmium (Ho, 67), and hassium (Hs, 108).
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PRACTICE QUESTIONS
1. QUESTION: Name one element with atomic number greater than twenty whose symbol begins with the letter B.
ANSWER: Bromine (Br), Barium (Ba), Bismuth (Bi), Berkelium (Bk) or Bohrium (Bh)
SOLUTION:
Boron (B, 5) and beryllium (Be, 4) begin with B but have atomic numbers below twenty.
2. QUESTION: Name one element with atomic number greater than twenty whose symbol begins with the letter Z.
ANSWER: Zinc (Zn) or Zirconium (Zr)
SOLUTION:
Zinc is element 30 and zirconium is element 40; no other symbol begins with Z.
3. QUESTION: Name one element with atomic number less than thirty whose symbol has two letters and begins with the letter N.
ANSWER: Neon (Ne), Sodium (Na) or Nickel (Ni)
SOLUTION:
Ne is 10, Na is 11 and Ni is 28; nitrogen's symbol N has only one letter.
4. QUESTION: Name the element with atomic number greater than twenty whose symbol begins with the letter X.
ANSWER: Xenon (Xe)
SOLUTION:
Xenon is element 54, a noble gas; no other symbol begins with X.
5. QUESTION: Name one element with atomic number less than twenty whose symbol begins with the letter S.
ANSWER: Silicon (Si) or Sulfur (S)
SOLUTION:
Si is 14 and S is 16; scandium (Sc, 21) and selenium (Se, 34) are beyond twenty.
6. QUESTION: Name one element with atomic number greater than fifty whose symbol begins with the letter P.
ANSWER: Praseodymium (Pr), Promethium (Pm), Platinum (Pt), Lead (Pb), Polonium (Po), Protactinium (Pa) or Plutonium (Pu)
SOLUTION:
Phosphorus (P, 15) and palladium (Pd, 46) begin with P but are below fifty.