Kerala SSLC · Chemistry · Class 10
Periodic Table and Electronic Configuration: Important Questions with Answers
These are 10 important multiple-choice questions from the Kerala SSLC Chemistry chapter “Periodic Table and Electronic Configuration” (Kerala SCERT syllabus). Each one shows the correct answer and a short explanation of why it is right. Try answering before you read the answer. ExamSummary has 10 practice questions on this chapter in total.
Q1.According to the Modern Periodic Law, the physical and chemical properties of elements are periodic functions of their...
- A)atomic masses
- B)atomic numbers
- C)mass numbers
- D)neutron counts
Answer: B) atomic numbers
Henry Moseley proved that atomic number (the number of protons) is the fundamental property governing periodicity, rather than atomic mass.
Q2.An element has an electronic configuration of 2, 8, 7. To which group of the Modern Periodic Table does it belong?
- A)Group 7
- B)Group 17
- C)Group 8
- D)Group 1
Answer: B) Group 17
The element has 7 valence electrons. In the modern table, elements with 7 valence electrons belong to Group 17 (Halogens).
Q3.How does the atomic size change when moving from left to right across a period in the Modern Periodic Table?
- A)Increases significantly
- B)Decreases
- C)Remains constant
- D)Fluctuates randomly
Answer: B) Decreases
As we move across a period, protons are added to the nucleus while electrons enter the same shell, increasing effective nuclear charge and pulling electrons closer.
Q4.What is the maximum number of electrons that can be accommodated in the 'M' shell of an atom?
- A)2
- B)8
- C)18
- D)32
Answer: C) 18
Using the formula 2n², where n=3 for the M shell, the maximum capacity is 2 × 3² = 18 electrons.
Q5.Which element posed a significant challenge regarding its position in Mendeleev's Periodic Table?
- A)Helium
- B)Hydrogen
- C)Oxygen
- D)Iron
Answer: B) Hydrogen
Hydrogen resembles both alkali metals (Group 1) and halogens (Group 17), making its unique placement difficult in Mendeleev's arrangement.
Q6.An element X has the electronic configuration 2, 8, 3. What is the valency of this element?
- A)1
- B)2
- C)3
- D)5
Answer: C) 3
The element has 3 valence electrons in its outermost shell. Metals tend to lose these electrons to achieve stability, giving it a valency of 3.
Q7.Why are noble gases placed in a separate group (Group 18) in the Modern Periodic Table?
- A)They are highly reactive with oxygen
- B)They have zero valency due to stable octets
- C)They exist only in gaseous state
- D)They were discovered very recently
Answer: B) They have zero valency due to stable octets
Noble gases have completely filled outermost electron shells (stable octet or duplet), making them chemically inert with zero valency.
Q8.Newlands' Law of Octaves was found to be valid only up to which element?
- A)Hydrogen
- B)Calcium
- C)Uranium
- D)Neon
Answer: B) Calcium
Newlands' pattern broke down after Calcium because heavier elements did not fit the octave pattern due to the discovery of new elements.
Q9.The period number of an element in the Modern Periodic Table indicates the number of...
- A)protons in the nucleus
- B)electron shells occupied
- C)valence electrons
- D)neutrons in the atom
Answer: B) electron shells occupied
The period number corresponds to the principal quantum number, which represents the total number of occupied electron shells in the atom.
Q10.Among the following elements, which one exhibits the highest metallic character?
- A)Fluorine (F)
- B)Chlorine (Cl)
- C)Sodium (Na)
- D)Magnesium (Mg)
Answer: C) Sodium (Na)
Metallic character decreases across a period; Sodium is furthest to the left in Period 3 compared to Mg, Cl, and F, making it the most metallic.