Atomic Structure and Bonding Quiz - ICSE Class 9 Chemistry

Free practice quiz: Atomic Structure and Bonding (ICSE Class 9 Chemistry). 50 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which of the following quantum numbers describes the orientation of an atomic orbital in space?

   1. Principal quantum number (n)
   2. Azimuthal quantum number (l)
   3. Magnetic quantum number (ml)
   4. Spin quantum number (ms)
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   Answer: C. Magnetic quantum number (ml)

   The principal quantum number (n) determines the energy level and size of an atomic orbital. The azimuthal quantum number (l) determines the shape of an atomic orbital. The magnetic quantum number (ml) determines the orientation of an atomic orbital in space. The spin quantum number (ms) describes the intrinsic angular momentum of an electron.

2. Which element has the electronic configuration 1s²2s²2p⁶3s¹?

   1. Sodium (Na)
   2. Magnesium (Mg)
   3. Aluminum (Al)
   4. Silicon (Si)
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   Answer: A. Sodium (Na)

   The atomic number of Sodium (Na) is 11. Its electronic configuration is 1s²2s²2p⁶3s¹. Magnesium (Mg) has atomic number 12 (1s²2s²2p⁶3s²). Aluminum (Al) has atomic number 13 (1s²2s²2p⁶3s²3p¹). Silicon (Si) has atomic number 14 (1s²2s²2p⁶3s²3p²).

3. Which of the following elements is diamagnetic?

   1. Oxygen (O₂)
   2. Nitrogen (N₂)
   3. Neon (Ne)
   4. Sulfur (S)
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   Answer: C. Neon (Ne)

   Diamagnetic substances are weakly repelled by an external magnetic field. This occurs when all electrons in the atom or molecule are paired. Oxygen (O₂) has unpaired electrons and is paramagnetic. Nitrogen (N₂) has all paired electrons in its molecular orbital diagram. Neon (Ne) has a full electron shell with all paired electrons. Sulfur (S) in its elemental form has unpaired electrons. Therefore, Neon is diamagnetic.

4. Which type of bond is responsible for holding the atoms together in a diatomic molecule of oxygen (O₂)?

   1. Ionic bond
   2. Single covalent bond
   3. Double covalent bond
   4. Triple covalent bond
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   Answer: C. Double covalent bond

   Oxygen atoms achieve a stable octet by sharing two pairs of electrons, forming a double covalent bond (O=O) in the O₂ molecule.

5. Which of the following has the largest atomic radius?

   1. Fluorine (F)
   2. Chlorine (Cl)
   3. Bromine (Br)
   4. Iodine (I)
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   Answer: D. Iodine (I)

   Atomic radius generally increases as you move down a group. Fluorine, Chlorine, Bromine, and Iodine are all in Group 17 (halogens). As you move down the group, the number of electron shells increases, and the valence electrons are further from the nucleus, leading to a larger atomic radius. Thus, Iodine has the largest atomic radius.

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