NCERT Exemplar solutions for Science [English] Class 10 chapter 5 - Periodic Classification of Elements [Latest edition]

Upto which element, the Law of Octaves was found to be applicable

According to Mendeléev's Periodic Law, the elements were arranged in the periodic table in the order of

In Mendeléev’s Periodic Table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later

Which of the following statement (s) about the Modern Periodic Table are incorrect

1. The elements in the Modern Periodic Table are arranged on the basis of their decreasing atomic number
2. The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic masses
3. Isotopes are placed in adjoining group (s) in the Periodic Table
4. The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic number

Which of the following statements about the Modern Periodic Table is correct:

Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period?

The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belong to the same group?

Where would you locate the element with electronic configuration 2,8 in the Modern Periodic Table?

An element which is an essential constituent of all organic compounds belongs to

Which of the following is the outermost shell for elements of period 2?

Which one of the following elements exhibit maximum number of valence electrons?

Which of the following gives the correct increasing order of the atomic radii of O, F and N?

Which among the following elements has the largest atomic radii?

Which of the following elements would lose an electron easily?

Which of the following elements does not lose an electron easily?

Which of the following are the characteristics of isotopes of an element?

1. Isotopes of an element have same atomic masses
2. Isotopes of an element have same atomic number
3.  Isotopes of an element show same physical properties
4. Isotopes of an element show same chemical properties

Arrange the following elements in the order of their decreasing metallic character

Na, Si, Cl, Mg, Al

Arrange the following elements in the order of their increasing nonmetallic character

Li, O, C, Be, F

What type of oxide would Eka– aluminium form?

Three elements B, Si and Ge are

Which of the following elements will form an acidic oxide?

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?

Which one of the following depict the correct representation of atomic radius(r) of an atom?

Which one of the following does not increase while moving down the group of the periodic table?

On moving from left to right in a period in the periodic table, the size of the atom.

Which of the following set of elements is written in order of their increasing metallic character?

Elements have been arranged in the following sequence on the basis of their increasing atomic masses.

Can the following groups of elements be classified as Döbereiner's triad?

1. Na, Si, Cl
2. Be, Mg, Ca

Compare the radii of two species X and Y. Give reasons for your answer.

1. X has 12 protons and 12 electrons
2. Y has 12 protons and 10 electrons

Arrange the following elements in increasing order of their atomic radii.

1. Li, Be, F, N
2. Cl, At, Br I

Identify and name the metals out of the following elements whose electronic configurations are given below.

1.  2, 8, 2
2. 2, 8, 1
3. 2, 8, 7
4. 2, 1

Arrange the following elements in the increasing order of their metallic character

Identify the elements with the following property and arrange them in increasing order of their reactivity

1. An element which is a soft and reactive metal
2. The metal which is an important constituent of limestone
3. The metal which exists in liquid state at room temperature

An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.

1. Identify the element
2. Write the electronic configuration
3. Write the balanced equation when it burns in the presence of air
4. Write a balanced equation when this oxide is dissolved in water
5. Draw the electron dot structure for the formation of this oxide

An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a divalent halide.

1. Where in the periodic table are elements X and Y placed?
2. Classify X and Y as metal (s), non-metal (s) or metalloid (s)
3. What will be the nature of oxide of element Y? Identify the nature of bonding in the compound formed
4. Draw the electron dot structure of the divalent halide

Atomic number of a few elements are given below
10, 20, 7, 14

1. Identify the elements
2. Identify the Group number of these elements in the Periodic Table
3. Identify the Periods of these elements in the Periodic Table
4. What would be the electronic configuration for each of these elements?
5. Determine the valency of these elements

Complete the following cross word puzzle 

Across:

(1) An element with atomic number 12.

(3) Metal used in making cans and member of Group 14.

(4) A lustrous non-metal which has 7 electrons in its outermost shell.

Down:

(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene.

(5) The first element of second Period

(6) An element which is used in making fluorescent bulbs and is second member of Group 18 in the Modern Periodic Table

(7) A radioactive element which is the last member of halogen family.

(8) Metal which is an important constituent of steel and forms rust when exposed to moist air.

(9) The first metalloid in Modern Periodic Table whose fibres are used in making bullet-proof vests

1. In below ladder symbols of elements are jumbled up. Rearrange these symbols of elements in the increasing order of their atomic number in the Periodic Table.
2. Arrange them in the order of their group also.

Mendeléev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.

1. Name the elements which have taken the place of these elements
2. Mention the group and the period of these elements in the Modern Periodic Table.
3. Classify these elements as metals, non-metals or metalloids
4. How many valence electrons are present in each one of them?

1. Electropositive nature of the element(s) increases down the group and decreases across the period
2. Electronegativity of the element decreases down the group and increases across the period
3. Atomic size increases down the group and decreases across a period (left to right)
4. Metallic character increases down the group and decreases across a period.

On the basis of the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.

1. Name the most electropositive element among them
2. Name the most electronegative element
3. Name the element with smallest atomic size
4. Name the element which is a metalloid
5. Name the element which shows maximum valency.

An element X which is a yellow solid at room temperature shows catenation and allotropy. X forms two oxides which are also formed during the thermal decomposition of ferrous sulphate crystals and are the major air pollutants.

1. Identify the element X
2. Write the electronic configuration of X
3. Write the balanced chemical equation for the thermal decomposition of ferrous sulphate crystals?
4. What would be the nature (acidic/ basic) of oxides formed?
5. Locate the position of the element in the Modern Periodic Table.

An element X of group 15 exists as diatomic molecule and combines with hydrogen at 773 K in presence of the catalyst to form a compound, ammonia which has a characteristic pungent smell.

1. Identify the element X. How many valence electrons does it have?
2. Draw the electron dot structure of the diatomic molecule of X. What type of bond is formed in it?
3. Draw the electron dot structure for ammonia and what type of bond is formed in it?