Directions: In the following question, a number sequence is given with one term missing. Choose the correct term that will continue the same pattern and replace the question mark in the given sequence.180,140,179,138,177,134,?
Correct answer: B. 174
- A. 120
- B. 174
- C. 128
- D. 175
Explanation
To solve the sequence 180, 140, 179, 138, 177, 134, ?, separate the terms by their positions:Odd-position terms: 180, 179, 177Even-position terms: 140, 138, 134For odd-position terms:180 → 179 (−1)179 → 177 (−2)The pattern suggests decreasing by 1 more than the previous step. Thus, 177 − 3 = 174.For even-position terms:140 → 138 (−2)138 → 134 (−4)The pattern suggests decreasing by 2 more than the previous step. Thus, 134 − 6 = 128, but this is irrelevant for the missing term, which is in the odd position.Thus, the correct answer is 174 as it follows the pattern for the odd-position terms. Options 120 and 175 do not fit either pattern, and 128 is for even positions, not applicable here.
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About Transition Elements
Transition elements are identified by their partially filled d subshells in atoms or common ions. The topic covers the electronic structure of d-block elements, including the filling order of 4s and 3d orbitals, variable oxidation states and the distinction between transition elements and elements with completely filled d subshells.
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