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NTSE Olympiad Science — practice questions

Explore 30 free Olympiad Science questions in NTSE Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Olympiad Science questions and exercises with answers

Showing questions 1–30 of 30.

An atom is stable when its valence shell holds a full set of electrons called an:Read the answer and worked solution →To reach that stable arrangement, atoms may lose, gain or:Read the answer and worked solution →Two hydrogen atoms joining together form a molecule of an:Read the answer and worked solution →Hydrogen and chlorine atoms joining together form a molecule of a:Read the answer and worked solution →Noble gases exist as single atoms because their atoms are already:Read the answer and worked solution →The force that holds two bonded atoms together is called a chemical:Read the answer and worked solution →A bond formed when two atoms share a pair of electrons is called:Read the answer and worked solution →A shared electron pair makes the molecule stable because it attracts both:Read the answer and worked solution →A hydrogen atom has one electron, so to become stable it needs one:Read the answer and worked solution →Each chlorine atom in a chlorine molecule needs to gain a share of electrons numbering:Read the answer and worked solution →In an oxygen molecule the two atoms share two pairs, which makes a bond that is:Read the answer and worked solution →In a water molecule, hydrogen completes not an octet but a:Read the answer and worked solution →An atom with more than four valence electrons will usually gain or share to complete its:Read the answer and worked solution →An atom with only one or two valence electrons will generally instead:Read the answer and worked solution →A sodium atom that loses its single valence electron becomes a positively charged:Read the answer and worked solution →A chlorine atom that gains an electron becomes a negatively charged:Read the answer and worked solution →Sodium and chloride ions are then held together by a force that is:Read the answer and worked solution →A bond formed by that transfer and attraction is called:Read the answer and worked solution →Ionic compounds are built as three-dimensional structures called:Read the answer and worked solution →In sodium chloride, the number of chloride ions surrounding each sodium ion is:Read the answer and worked solution →The repeating pattern of ions in such a solid is represented as a crystal:Read the answer and worked solution →The chemical formula of common salt, used as the standard ionic example, is:Read the answer and worked solution →Catch the bonding wordsRead the answer and worked solution →Pop the routes to stabilityRead the answer and worked solution →Run the bonding gatesRead the answer and worked solution →Slice the chemistry wordsRead the answer and worked solution →Covalent or ionicRead the answer and worked solution →Sort the bonding wordsRead the answer and worked solution →Type the numberRead the answer and worked solution →Bonding bingoRead the answer and worked solution →

Worked practice questions

An atom is stable when its valence shell holds a full set of electrons called an:

  1. Octet
  2. Orbit
  3. Offset
  4. Outlet
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Correct answer: A. Octet

1. A full outer shell leaves nothing to gain or lose. 2. For most atoms that means eight electrons. 3. That full set is an octet. _Source: syllabus Science Class IX, Chapter 9, Atomic Foundations of Matter._

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To reach that stable arrangement, atoms may lose, gain or:

  1. Shuffle
  2. Share
  3. Shrink
  4. Shatter
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Correct answer: B. Share

1. Losing and gaining are two of the three routes. 2. The third lets two atoms use the same electrons. 3. That third route is sharing. _Source: syllabus Science Class IX, Chapter 9, Atomic Foundations of Matter._

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Two hydrogen atoms joining together form a molecule of an:

  1. Element
  2. Emulsion
  3. Equation
  4. Extract
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Correct answer: A. Element

1. Both atoms are the same kind. 2. No second element takes part. 3. So it is a molecule of an element. _Source: syllabus Science Class IX, Chapter 9, Atomic Foundations of Matter._

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More Chemistry topics

ChemistryCarbon and its CompoundsChemical BondingNTSE Science