Solved Practice Questions on Group 15 & 16 Elements: Nitrogen and Oxygen Family | Inorganic Chemistry PDF Download

Q.1. Which of the following represents the general electronic configuration of an element belonging to the p-block of the periodic table?
(a) (n-2)f⁰(n-1)d⁰ns² np^{0 -6}
(b) (n-2)f⁰(n-1)d^{1 – 10} ns² np^{1- 6}
(c) (n-2)f⁰(n-1)d⁰ ns²np^1-6
(d) (n-2)f^{1- 14}(n-1)d^{1- 10}ns²np^{1- 6} 

Correct Answer is Option (c)
The general configuration representation of p-block elements is (n-2)f⁰(n-1)d⁰ns²np^1-6. This is because the s-subshell is completely filled, whereas, the p-subshell contains at least 1 electron. Other options are ruled out since either or both d – and f – subshell are partially filled.

Q.2. Group 16 elements are also called Chalcogens.
(a) True
(b) False

Correct Answer is Option (a)
Group 16 elements, also known as the Oxygen family, are also called Chalcogens (pronounced as kal’-ke-jens) (meaning ore forming elements) because many metals occur as oxides and sulphides.

Q.3. What happens to the size of atoms of elements of p-block as we move from left to right in the same period?
(a) Size increases
(b) Size decreases
(c) Size does not change
(d) Size increases then decreases

Correct Answer is Option (b)
The size of the atoms of the elements decrease from left to right in the same period. Considering the row to be the same, the electrons are added to the same shell. However, the increase in atomic number reflects the increase in number of protons i.e. the positive charge. Hence, the overall effective nuclear charge increases. Consequently, the electron cloud is pulled even more closer to the nucleus of the atom. Therefore, the size decreases. 

Q.4. Which of the following elements does not belong to group 16 of the periodic table?
(a) Oxygen
(b) Phosphorus
(c) Sulphur
(d) Selenium

Correct Answer is Option (b)
Group 16 of the periodic table consists of five elements viz., Oxygen (O), Sulphur (S), Selenium (Se), Tellurium (Te) and Polonium (Po). The elements of this group are commonly known as the oxygen family after the name of its first member. 

Q.5. What is the maximum covalency of the nitrogen atom?
(a) One
(b) Two
(c) Three
(d) Four

Correct Answer is Option (d)
Covalency of an atom refers to the number of electrons that atom can share to form chemical bonds. Usually it is the number of bonds formed by the atom. In case of nitrogen, its atom can share up to four electrons, one in the s-subshell and the other three in the p-subshell. In addition to this, absence of d-orbitals restricts its covalency to four only. 

Q.6. Which is the most abundant group 16 element?
(a) Oxygen
(b) Sulphur
(c) Selenium
(d) Tellurium

Correct Answer is Option (a)
Oxygen is the most abundant of all elements. It occurs in the free state as dioxygen (O₂) and makes up 20.46% by volume and 23% by mass of the atmosphere. It also occurs in the form of ozone (O₃). 

Q.7. Why does nitrogen show poor tendency towards catenation?
(a) N atom can form multiple pπ – pπ bonds
(b) Octet of N₂ is complete unlike carbon
(c) The N ≡ N is unreactive at room temperature
(d) The N – N single bond is weaker and unstable

Correct Answer is Option (d)
The N – N single bond is highly weak and unstable due to high magnitude of inter-electronic repulsions of non-bonding electrons which in turn is caused by the single bond’s small bond length. As a result the catenation tendency becomes weaker due to the mentioned factors leading to instability. 

Q.8. Ozone is an allotrope of Oxygen.
(a) True
(b) False

Correct Answer is Option (a)
Oxygen also occurs as ozone (O₃), an allotrope of oxygen, in the upper atmosphere which protects us from the harmful radiations of the sun. Ozone is a pale blue gas with a distinctively pungent smell. 

Q.9. What is the primary product of Haber-Bosch process?
(a) Ammonia
(b) Nitric acid
(c) Nitrous acid
(d) Pyridine

Correct Answer is Option (a)
The primary product of Haber-Bosch process is ammonia, NH₃. In this process, N_2(g) and H_2(g) are reacted at a high temperature of 700 K and 200 atm pressure in presence of iron-bed catalysts. It is an exothermic process which takes place in accordance with Le Chatelier’s principle. Nitric acid is produced by Ostwald’s process. Nitrous acid is produced by reacting sodium nitrite with a mineral and pyridine by Chichibabin process.

Q.10. What is the general outer electronic configuration of the Oxygen family?
(a) ns²np⁴
(b) ns²np³
(c) ns²np⁵
(d) ns²np² 

Correct Answer is Option (a)
The elements of group 16 have six electrons in the valence shell and hence their general outer electronic configuration is ns²np⁴. The four p-electrons are arranged in three p-orbitals as p_x²p_y¹p_z¹ in accordance with Hund’s rule. 

Q.11. Which of the following statements regarding group 16 elements is not true?
(a) The electronic configuration of Oxygen is [He]2s²2p⁴
(b) The electronic configuration of Sulphur is [Ne]3s²3p⁴
(c) The atomic radii of the elements of group 16 are larger than those of the corresponding elements of group 15
(d) The electronic configuration of Tellurium is [Kr]4d¹⁰5s²5p⁴ 

Correct Answer is Option (c)
When you move across the periodic table, from left to right, the atomic size of the respective elements decreases due to increase in nuclear charge. Therefore, the atomic radii of the elements of group 16 are smaller than those of the corresponding elements of group 15. 

Q.12. Which group 16 element is the most electronegative?
(a) Sulphur
(b) Polonium
(c) Oxygen
(d) Selenium

Correct Answer is Option (c)
The elements of group 16 have higher values of electronegativity than the corresponding elements of group 15. Actually, oxygen is the second most electronegative element (EN = 3.5), the first being fluorine (EN = 4.0). 

Q.13. Which of the following is radioactive in nature?
(a) Oxygen
(b) Sulphur
(c) Tellurium
(d) Polonium

Correct Answer is Option (d)
Oxygen is the most non-metallic element of group 16. Sulphur is also a typical non-metal and Tellurium is a metalloid. Polonium is, however, metallic in nature but is radioactive with a short half-life (13.8 days).

Q.14. Which of the following does not exist as an octatomic solid?
(a) Sulphur
(b) Tellurium
(c) Selenium
(d) Oxygen

Correct Answer is Option (d)
Oxygen exists as a diatomic gas at room temperature while other elements (S, Se and Te) exist as octatomic solids. Due to small size and high electronegativity, oxygen atom forms pπ – pπ double bond with other oxygen atom to form O = O molecule. The intermolecular forces of attraction between oxygen molecules are weak van der Waals forces and hence oxygen exists as a diatomic gas at room temperature. 

Q.15. Which group 16 element has the highest tendency for catenation?
(a) Oxygen
(b) Sulphur
(c) Selenium
(d) Polonium

Correct Answer is Option (b)
Sulphur has a stronger tendency for catenation than Oxygen. Due to small size, the lone pairs on the Oxygen atoms repel the bond pair of the O-O bond to a greater extent than the lone pairs of electrons on the Sulphur atoms in S-S bond. As a result, S-S bond is much stronger than O-O bond and hence Sulphur has a much stronger tendency for catenation than Oxygen.