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SSLC Chemistry Chapter 3 Important Questions Kerala Syllabus
Periodic Table and Electron Configuration Class 10 Important Questions
Question 1.
Which subshell is common to all shells?
Answer:
s subshell
Question 2.
What is the maximum number of electrons that can be accommodated in the s subshell?
Answer:
2 electrons
Question 3.
What is the range of possible values for the azimuthal quantum number (l) for a given principal quantum number (n)?
Answer:
The value of l ranges from zero to (n – 1).
Question 4.
If n = 3, what are the possible values of l and the corresponding subshells?
Answer:
If n = 3, the possible values of 1 are 0, 1, and 2. l = 0 denotes the s subshell. l = 1 denotes the p subshell. L = 2 denotes the d subshell.
Question 5.
What does the magnetic quantum number (m) represent?
Answer:
The magnetic quantum number (m) represents the difference in the orientation of orbitals in space.
Question 6.
What is the relationship between the value of the azimuthal quantum number (l) and the number of possible values for the magnetic quantum number (m)?
Answer:
For a particular value of l, there are (2l + 1) possible values for m.
Question 7.
Write down the subshell electronic configuration of Fe2+.
Answer:
1s22s22p63s23p63d6
Question 8.
How many orientations does an s orbital (l = 0) have? Explain.
Answer:
For an s orbital, l = 0. Therefore, the number of possible values for m is (2 × 0 + 1) = 1. This shows that an s orbital has only one spatial orientation.
Question 9.
If l = 1 (p subshell), what are the possible values of m, and what does this indicate about the orientation of p orbitals?
Answer:
If l = 1, the possible values of m are -1, 0, and +1. This means that there are three different spatial orientations for p orbitals.
Question 10.
If l = 2, how many values will there be for m, and how many d orbitals does this correspond to?
Answer:
If l = 2, the number of possible values for m will be (2 × 2 + 1) = 5. This corresponds to five d orbitals, each with a different spatial orientation.
Question 11.
What is the formula for the total number of orbitals in a given principal energy level (shell) n?
Answer:
The formula for the total number of orbitals in a given shell n is n2.
Question 12.
What is the formula for the maximum number of electrons that can be accommodated in a given principal energy level (shell) n?
Answer:
The formula for the maximum number of electrons that can be accommodated in a given shell n is 2n2.
Question 13.
What is the maximum number of electrons that can be accommodated in a single orbital?
Answer:
The maximum number of electrons that can be accommodated in each orbital is 2.
Question 14.
What is the name given to the orbit of electrons around the nucleus within an atom?
Answer:
Shell (main energy level)
Question 15.
The subshell electron configuration of the two elements is given below. Write the chemical formula of the compound formed by them.
A – 1s22s22p63s23p1
B – 1s22s22p63s23p5
Answer:
AB3
(ions formed are A3+ and B1-).
Question 16.
How can you determine the maximum number of electrons that can be accommodated in a subshell with a given azimuthal quantum number (l)?
Answer:
The number of orbitals in a subshell with azimuthal quantum number l is (2l + 1). Since each orbital can hold a maximum of 2 electrons, the maximum number of electrons in that subshell is 2 × (2l + 1).
Question 17.
What changes in the following as the distance from the nucleus increases?
a) The energy of the electrons
b) The force of attraction between the nucleus and the electrons
Answer:
a) Increases.
b) Decreases.
Question 18.
The atomic number of an element is 11. (FIRST TERM 2022)
a) Write the sub-shell electronic configuration of this element.
b) What is the common oxidation state shown by this element?
Answer:
a) 1s22s22p63s1
b) +1
Question 19.
What is the number of orbitals in the p subshell? What is the maximum number of electrons it can accommodate?
Answer:
The number of orbitals in a p subshell (l = 1) is 3. Therefore, the maximum number of electrons it can accommodate is 3 × 2 = 6.
Question 20.
Which of the following is not correct in the subshell electron configuration?
a) 1s22s22p7
b) 1s22s22p2
c) 1s22s22p53s1
d) 1s22s22p63s23p63d24s1
e) 1s22s22p63s23p63d24s2
Answer:
The incorrect subshell electron configuration are
a) 1s22s22p7
c) 1s22s22p53s1
d) 1s22s22p63s23p63d24s1
Question 21.
Outermost Subshell electron configuration of two elements X and Y are given.
X = 3s2; Y = 3s23p5 (Symbols are not real)
(a) What is the valency of the element X?
(b) Which element shows metallic character?
(c) Write the chemical formula of the compound formed by the combination of X and Y? (MARCH 2021)
Answer:
a) 2
b) X
c) XY2
Question 22.
The atoms of elements A and B contain 3 shells each (symbols are not real). (MODEL 2023)
A belongs to group 2, and B belongs to group 16.
(a) Write the subshell electron configuration of A.
(b) What is the valency of element B?
(c) Write the chemical formula of the compound formed by the reaction of A and B?
Answer:
(a) 12A – 1s22s22p63s2
(b) 16B – 1s22s22p63s23p6
Valency = 2
(c) Valency of A = 2 Valency of B =2 Chemical formula = AB
Question 23.
Complete the table by writing the subshell electron configuration of the given elements.
Answer:
| Element | Number of electrons | Subshell electronic configuration |
| 7N | 7 | 1s22s22p3 |
| 9F | 9 | 1s22s2p5 |
| 11Na | 11 | 1s22s22p63s1 |
| 17Cl | 17 | 1s2s2p63s23p5 |
| 8Ar | 18 | 1s22s22p63s23p6 |
Question 24.
Element X, group number 17, has 3 shells. If
a) Write the subshell electron configuration of this element.
b) What is the period number?
c) What will be the chemical formula of the compound formed when X reacts with an atom of element Y, in the third period, which has one electron in the p subshell?
Answer:
a) 1s22s22p63s23p5
b) 3
c) The electron configuration of Y = 1s22s22p63s23p1
Ions X–Y3+
Chemical formula of compound – YX3
Question 25.
The element Cu, with atomic number 29, undergoes a chemical reaction to form an ion with an oxidation state of +2.
a) Write the subshell electron configuration of this ion.
b) Is it possible for this element to exhibit a different oxidation state? Why?
c) Write the chemical formula of a compound formed when this element reacts with chlorine.
Answer:
a) 1s22s22p63s23p63d9
b) Yes. Being a d block element, there is only a very small difference in the energy levels of electrons in 4s and 3d.
c) CuCl2
Question 26.
Subshell electron configuration of certain elements are given below
A – 1s22s22p63s2
B – 1s22s22p4
C – 1s22s22p63s23p6
D – 122s22p63s23p63d64s2
i) Write the atomic number of the element ‘A’.
ii) Which is the inert gas among them?
iii) The element ‘D’ can form coloured compounds. Explain the reason.
iv) Write the chemical formulae of the compound formed by the elements A and B.
Answer:
i) 11
ii) C
iii) D – Transition elements
iv) A2B
Question 27.
What are stationary energy levels according to the Bohr model of the atom?
Answer:
According to the Bohr model, orbits have definite energy, and these orbits are known as stationary energy levels.
Question 28.
Explain how the discovery of the wave nature of matter contributed to the limitations of the Bohr model.
Answer:
The discovery of the wave nature of matter revealed that electrons exhibit both particle and wave
properties. The Bohr model considered electrons solely as particles moving in fixed orbits, failing to incorporate their wave-like behaviour.
Question 29.
Mention two significant limitations of the Bohr model of the atom.
Answer:
Two significant limitations are:
- It does not account for the wave nature of matter, which is significant for microscopic particles like electrons.
- It contradicts Heisenberg’s Uncertainty Principle by suggesting that the exact position and velocity of an electron can be simultaneously determined.
Question 30.
What does the principal quantum number (n) represent?
Answer:
The principal quantum number (n) is used to represent the shells or principal energy levels of an atom.
Question 31.
What are the possible values for the principal quantum number?
Answer:
The possible values for the principal quantum number are n = 1, 2, 3, 4,…
Question 32.
What property of an orbital does the azimuthal quantum number (l) define?
Answer:
The azimuthal quantum number (l) defines the three-dimensional shape of the orbital.
Question 33.
Shell wise electron configuration of an element is 2, 8, 8, 2.
On the basis of this, answer the following questions
a) Which are the subshells in each shell?
b) In which subshell the last electron is likely to be filled up?
c) In which period and block of the periodic table this element belongs to?
Answer:
(The atomic number of this element is 20.
Subshell electron configuration is 1s22s22p63s23p64s2 )
a) K – s; L – s, p; M – s, p; N – s
b) In 4s
c) 4th period and s block
Question 34.
Match the following
| Element | Atomic No | Electron configuration | Valency |
| A | 13 | 1s22s22p63s23p4 | 4 |
| B | 14 | 1s22s22p63s23p5 | 2 |
| C | 16 | 1s22s22p63s23p1 | 3 |
| D | 17 | 1s22s22p63s23p2 | 1 |
Answer:
| Element | Atomic No | Electron configuration | Valency |
| A | 14 | 1s22s22p63s23p2 | 4 |
| B | 13 | 1s22s22p63s3p1 | 3 |
| C | 16 | 1s22s22p63s23p4 | 2 |
| D | 17 | 1s22s22p63s23p5 | 1 |
Question 35.
Analyse the given table and answer the following questions:
| Element (Symbols are not real) | Atomic number |
| P | 11 |
| Q | 18 |
| R | 17 |
| S | 26 |
a) Identify the noble gas among these elements.
b) Identify the element belonging to Group 1.
c) Identify the type of compound formed by P and R.
d) Which is the element showing variable valency? Write the subshell electron configuration of the element?
Answer:
a) Q – 18
b) P – 11
c) Ionic compound
d) S – 26
S – 1s22s22p63s23p63s23d64s2
Question 36.
Two ions formed by copper are Cu+ and Cu2+
a) Which are the subshell/subshells from which electrons are lost?
b) Find out the number of electrons in Cu+ and Cu2+.
Answer:
a) Cu+ – one electron is lost from 4s
Cu2+ – one electron is lost from 4s and 1 electron from 3d
b) Cu+ = 28 electrons; Cu2+ = 27 electrons
Question 37.
Define ionisation enthalpy of an element.
Answer:
The ionisation enthalpy of an element is the minimum amount of energy required to remove the most loosely bound electron from the outermost shell of an isolated gaseous atom of the element.
Question 38.
What happens to the number of shells as you move down a group in the periodic table?
Answer:
Increases.
Question 39.
Summarise the trend in ionisation enthalpy as you move down a group in the periodic table and explain why.
Answer:
Ionisation enthalpy decreases on moving down a group. This is because the increasing number of electron shells increases the distance between the nucleus and the outermost electrons, and also increases the shielding effect. Both factors reduce the effective nuclear charge experienced by the outermost electrons, making them easier to remove.
Question 40.
Explain why ionisation enthalpy generally increases across a period.
Answer:
On moving from left to right in a period, the number of electron shells remains the same, but the nuclear charge increases gradually. This increased nuclear charge pulls the outermost electrons more strongly towards the nucleus, resulting in a stronger attractive force. Consequently, more energy is required to remove an electron, leading to an increase in ionisation enthalpy.
Question 41.
Which block of elements generally has a lower ionisation enthalpy compared to other blocks?
Answer:
The s-block elements, specifically alkali metals, generally have lower ionization enthalpies compared to elements in other blocks. This is because alkali metals have a larger atomic size and a lower effective nuclear charge, making it easier to remove their single valence electron.
Question 42.
What are the typical oxidation states exhibited by Group 1 and Group 2 elements (s block elements)? Answer:
The elements of Group 1 exhibit a +1 oxidation state, and the elements of Group 2 exhibit a +2 oxidation state.
Question 43.
Which groups in the periodic table include the p block elements?
Answer:
p block elements are seen in groups 13 to 18.
Question 44.
In d block elements, which electron shell is being gradually filled with electrons?
Answer:
The penultimate shell (the shell just before the outermost shell).
Question 45.
In f block elements, in which subshell does the filling up of electrons take place?
Answer:
Anti-penultimate f subshell.
Question 46.
Write the uses and characteristics of f block elements.
Answer:
- They show variable oxidation states.
- Actinoids are radioactive elements. These include man-made elements as well.
- Certain isotopes of elements like Uranium (U), Thorium (Th) and Plutonium (Pu) are used as fuel in nuclear reactors.
- Neodymium (Nd) is used for making strong magnets.
- Some elements are used as catalyst in the petroleum industry. For example:- Cerium (Ce), Lanthanum (La).