Periodic Classification of Elements Class 10 MCQs Questions with Answers
Question 1.
Which of the following statements) about the modern periodic table are incorrect?
(I) The elements in the modern periodic table are arranged on the basis of their decreasing atomic numbers.
(II) The elements in the modern periodic table are arranged on the basis of their increasing atomic masses.
(III) Isotopes are placed in adjoining group(s) in the periodic table.
(IV) The elements in the modern periodic table are arranged on the basis of their increasing atomic number.
(a) Only (I)
(b) (I), (II), and (III)
(c) (I), (II), and (IV)
(d) Only (IV)
Answer:
(b) (I), (II), and (III)
Explanation: The modern periodic table is a tabular arrangement of elements in increasing order of their atomic number, which is why isotopes are placed at the same position. Hence, only (III) is correct.
Question 2.
Which of the following statements about the modern periodic table is correct?
(a) It has 18 horizontal rows known as periods.
(b) It has 7 vertical columns rows known as periods.
(c) It has 18 vertical columns known as groups.
(d) It has 7 horizontal rows known as groups.
Answer:
Question 3.
An element X is forming the acidic oxide. Its most probable position in the modern periodic table is:
(a) Group 1 and Period 3
(b) Group 16 and Period 3
(c) Group 17 and Period 3
(d) Group 2 and Period 3
Answer:
Question 4.
Which of the given elements A, B, C, D and E with atomic numbers 2, 3, 7,10 and 30 respectively belong to the same period?
(a) A, B, C
(b) B, C, D
(c) A, D, E
(d) B, D, E
Answer:
Question 5.
On the basis of the electronic configuration of x|, the group number and period of the element ‘X is:
(a) Group 15 period 2
(b) Group 13 period 2
(c) Group 9 period 5
(d) Group 13 period 5
Answer:
(b) Group 13 period 2
Explanation: From X95, we can have the information as:
X — element
5 — Atomic number
9 — Mass number
The electronic configuration of X is 2, 3.
Group number is found out on the basis of valance electrons. Valence electrons are 3 so group number is 10 + 3 = 13.
Period can be found out by knowing the number of shells. Since a number of shells is 2 so it belongs to period 2.
Question 6.
The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively.
Which pair of elements belongs to the same group?
(a) A and B
(b) B and D
(c) A and C
(d) D and E
Answer:
Question 7.
An element ‘X‘ with atomic number 11 forms a compound with element ‘V with atomic number 8. The formula of the compound formed is:
(a) XY
(b) X2Y
(c) XY2
(d) X2Y3
Answer:
(b) X2Y
Element X can lose one electron and has a configuration like that of Neon.
X → X+ + e–
Element Y can gain two electrons to acquire noble gas configuration like that of Neon:
Y + 2e– → Y2–
Or we can write
Question 8.
The positions of four elements A, B, C, and D in the modern periodic table are shown below.
Which element is most likely to form an acidic oxide?
(a) A
(b) B
(c) C
(d) D
Answer:
Question 9.
In Mendeleev’s periodic table, gaps were left for the elements to be discovered later. Which of the following element found a place in the periodic table later?
(a) Germanium
(b) Chlorine
(c) Oxygen
(d) Silicon
Answer:
Question 10.
Elements P, Q, R, and S have atomic numbers 11,15,17 and 18 respectively. Which of them are reactive non-metals?
(a) P and Q
(b) P and R
(c) Q and R
(d) R and S
Answer:
(c) Q and R
Question 11.
An element which is an essential constituent of all organic compounds belongs to:
(a) Group 1
(b) Group 14
(c) Group 15
(d) Group 16
Answer:
Question 12.
According to Mendeleev’s periodic law, the elements were arranged in the periodic table in the order of:
(a) Increasing atomic number
(b) Decreasing atomic number
(c) Increasing atomic masses
(d) Decreasing atomic masses
Answer:
(c) Increasing atomic masses
Explanation: Mendeleev’s periodic law is an arrangement of elements in increasing order of their atomic masses as Mendeleev’s periodic law states that, the physical and chemical properties of elements are a periodic function of their atomic masses.
Question 13.
Which of the following is the outermost shell for elements of period 2?
(a) K shell
(b) L shell
(c) M shell
(d) N shell
Answer:
Question 14.
Which of the following gives the correct increasing order of the atomic radii of O, F, and N?
(a) O, F, N
(b) N, F, O
(c) O, N, F
(d) F, O, N
Answer:
Question 15.
Arrange the following elements in the order of their decreasing metallic character Na, Si, Cl, Mg, Al:
(a) Cl > Si > Al > Mg > Na
(b) Na > Mg > Al > Si > Cl
(c) Na > Al > Mg > Cl > Si
(d) Al > Na > Si > Ca > Mg
Answer:
Question 16.
Which among the following elements has the largest atomic radii?
(a) Na
(b) Mg
(c) K
(d) Ca
Answer:
(c) K
Explanation: Na and Mg belong to the same period, whereas Na and K are in the same group. In a group from top to bottom, the atomic radius increases, whereas it decreases in a period from left to right. Hence, the order would be K > Na > Mg and K > Ca > Mg.
Related Theory
Atomic radius represents the distance from the nucleus to the outer shell of an element.
Trend of the atomic radius in the periodic table:
(1) decreases going from left to right of a period
(2) increases going down a group.
Question 17.
The electronic configurations of three elements X, Y and Z are:
X : 2 Y: 2, 8, 7 Z : 2, 8, 2
Which of the following is correct regarding these elements?
(a) X is a metal
(b) Y is a metal
(c) Z is a non-metal
(d) Y is a non-metal and Z is a metal
Answer:
(d) Y is a non-metal and Z is a metal.
Explanation: Element Y has 1 less electron to complete its octet which is a property of non-metals. On the other hand, element Z has 2 extra electrons to become stable which is a property of metals..
Question 18.
Which of the following elements would lose an electron easily?
(a) Mg
(b) Na
(c) K
(d) Ca
Answer:
Question 19.
Which of the following elements does not lose an electron easily?
(a) Na
(b) F
(c) Mg
(d) Al
Answer:
(b) F
Explanation: Flourine has 7 electrons in the outermost orbit. Its atom size is the smallest too. Since it is the most electronegative element, it does not lose an electron easily. Sodium has one valence electron, magnesium has 2 valence electrons, and aluminium has 3 valence electrons. All these metals lose electrons easily.
Related Theory
Metals can easily lose electrons and exhibit electropositive nature, whereas non-metals have a tendency to accept electrons and exhibit electronegative nature. Na, Al, and Mg are metals, whereas F is non-metal.
Question 20.
What type of oxide would Eka-aluminium form?
(a) EO3
(b) E3O2
(c) E2O3
(d) EO
Answer:
Question 21.
The element with atomic number 14 is hard and forms acidic oxide and a covalent halide. To which of the following categories does the element belong?
(a) Metal
(b) Metalloid
(c) Non-metal
(d) Left-hand side element
Answer:
(b) Metalloid
Explanation: Atomic number 14 (electronic configuration of 2,8,4) is for silicon element, which is a metalloid and exhibits properties of both metal and non-metal. It has 4 electrons in its valence shell, so it tends to form covalent acidic oxide.
Question 22.
Which one of the following depicts the correct representation of atomic radius (r) of an atom?
(a) (I) and (II)
(b) (II) and (III)
(c) (III) and (IV)
(d) (I) and (IV)
Answer:
(b) (II) and (III)
Explanation: The distance between the center of the nucleus and the outermost shell is known as atomic radius.
Question 23.
Which one of the following does not increase while moving down the group of the periodic table?
(a) Atomic radius
(b) Metallic character
(c) Valence
(d) Number of shells in an element
Answer:
Question 24.
On moving from left to right in a period in the periodic table, the size of the atom:
(a) increases
(b) decreases
(c) does not change appreciably
(d) first decreases and then increases
Answer:
(b) decreases
Explanation: As we move from left to right in the period of periodic table, the number of shell remains same but atomic number increases. So, the increase in nuclear charge which tends to pull electrons closer to the nuclers and reduces the size of the atoms.
Related Theory
The size of atom of an inert gas is bigger than that of the preceding halogen atom. The greater size of the inert gas atom in a period is due to the structural stability of its outermost shell consisting of an octet of electrons.
Question 25.
Which of the following set of elements is written in order of their increasing metallic character?
(a) Be, Mg, Ca
(b) Na, Li, K
(c) Mg, Al, Si
(d) C, O, N
Answer:
(a) Be, Mg, Ca.
Explanation: As we move down in a group, the metallic nature of elements increases. Be, Mg, and Ca are present in the same group (group 2 of the modern periodic table). Thus, Ca has the highest metallic character.
Question 26.
An element X makes an oxide with the formula X2O3. This element will be in the same group as:
(a) Na
(b) Mg
(c) Al
(d) Cl [Diksha]
Answer:
(c) Al
Explanation: The answer is Al (aluminium). The element Al is in group II! of Mendeleev’s periodic table, in which the general formula of the oxides of elements is X2O3.
Question 27.
The two pairs of elements placed by Newlands in one slot are:
(a) Co, Ni and Ce, La
(b) Be, Mg and Co, Ni
(c) F, Cl, and Ce, La
(d) Zn, Sr, and Be, Mg
Answer:
Question 28.
The order of metallic character of some elements is: N < P < As < Sb < Bi. Identify the most electronegative among these elements,
(a) N
(b) P
(c) Sb
(d) Bi
Answer:
(a) N
Explanation: The less metallic an element, the more electro-negative it will be. Since electronegativity is the ability of an atom to gain electrons, whereas metallic character is related to the ability of atoms to lose electrons. As N is the least metallic of the given elements, it will be the most electronegative.
Question 29.
Four elements P, Q, R and S have number of valence electrons 2,3,5 and 7 respectively. A student noted down the Group number in Modern Periodic Table and their valency as:
Select the row containing the correct group number and valency.
Answer:
Question 30.
Consider the elements Li, Be, B, C, N, O and F.
(I) The most electropositive element is F.
(II) The most electronegative element is F.
(III) The only metalloid is B.
(IV) The smallest atomic size is Li.
Read the statements given above and select the incorrect statements:
(a) Both (I) and (III)
(b) Both (I) and (IV)
(c) Both (II) and (III)
(d) Both (II) and (IV)
Answer:
(b) Both (I) and (IV)
Explanation: Let us arrange the given elements according to their atomic number:
Li < Be < B < C < N < 0 < F.
All the above elements have two occupied shells and are therefore placed in the second group of the periodic table.
The most electropositive element is Li and the most electronegative element is F. This is because the tendency to lose electrons decreases as we go from left to right along a period. Also, as we go from left to right along a period, the atomic radius and hence the atomic size decreases because of the increase in effective nuclear charge experienced by the valence electrons. The only metalloid is B.
Question 31.
Out of the elements F, Cl, Br and I, which is the most electronegative element?
(a) F
(b) Cl
(c) Br
(d) I
Answer:
(a) F
Explanation: The electronegativity decreases as we move down a group because the ability to gain electrons decreases down a group. This is because of the decrease in the effective nuclear charge experienced by the valence electrons since a new shell is added in each group.
Since F, Cl, Br and I have 2, 3, 4 and 5 shells respectively, F is the most electronegative of these elements.
Assertion Reasoning questions Class 10 Science Chapter 5
For the following questions, two statements are given-one labeled Assertion (A) and the other labeled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both (A) and (R) are true and (R) is the correct explanation of the assertion.
(b) Both (A) and (R) are true but (R) is not the correct explanation of the assertion.
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
Question 32.
Assertion (A): Potassium has a bigger atomic radius than lithium.
Reason (R): Atomic radius decreases along a period. [Diksha]
Question 33.
Assertion (A): Chemical properties of the elements belonging to the same group are the same.
Reason (R): Elements belonging to the same group possess the same number of valence electrons.
Answer:
(a) Both (A) and (R) are true and (R) is the correct explanation of A.
Question 34.
Assertion (A): Nitrogen is a non-metal.
Reason (R): Nitrogen has 5 valence electrons.
Answer:
(a) Both (A) and (R) are true and (R) is the correct explanation of (A)
Explanation: Non-metals are the elements that form negative ions by gaining electrons.
Electronic configuration of N = 2 5
k = 2
L = 5
It needs 3 electrons to complete its octet and achieve the same configuration as that of the inert gas neon.
N + 3e– → N3-
Question 35.
Assertion (A): Newland’s law of Octaves worked well with lighter elements only.
Reason (R): Newland assumed that only 56 elements existed in nature.
Question 36.
Assertion (A): A correct position could not be assigned to hydrogen in Mendeleev’s periodic table.
Reason (R): Mendeleev Periodic Law states that ‘the properties of elements are the periodic function of their atomic numbers.
Answer:
(c) (A) is true but (R) is false
Explanation: A correct position could not be assigned to hydrogen in the periodic table. The electronic configuration of hydrogen resembles that of alkali metals. Like alkali metals, hydrogen combines with halogens, oxygen and sulfur to form compounds having similar formulae.
On the other hand, just like halogens, hydrogen also exists as diatomic molecules and it combines with metals and non-metals to form covalent compounds.
Moreover, Mendeleev’s Periodic Law states that ‘the properties of elements are the periodic function of their atomic masses’.
Question 37.
Assertion (A): The elements Sodium (Na), Magnesium (Mg), Aluminium (Al) belong to the same group in Modern Periodic Table.
Reason (R): Atoms of different elements with the same number of occupied shells are placed in the same period.
Question 38.
Assertion (A): Calcium (Atomic No. 20) is more metallic than Potassium (Atomic No. 19).
Reason (R): The tendency to lose electrons decreases as we move from left to right in a period.
Answer:
(c) (A) is false but (R) is true.
Explanation: Potassium (Atomic No. 19) is more metallic than Calcium (Atomic No. 20) as the tendency to lose electrons decreases as we move from left to right in a period.
The electronic configuration of Potassium is 2, 8, 8, 1 and that of Calcium is 2, 8, 8, 2. Therefore, the effective nuclear charge acting on the valence electrons of Calcium will be more than that of Potassium.