Use Mendeleev's Periodic Table to predict the formulae for oxides of the following elements: K and Al .

The element K belongs to the first group of Mendeleev's periodic table. Its valency is 1 . The valency of oxygen is 2 . So, the formula of its oxide will be K 2 O . The elements belonging to the same group have a similar formula of oxides. So, the general formula for oxides of the elements of group 1 is R 2 O . Similarly, the valency of Al is 3 , so the formula of its oxide will be Al 2 O 3 .

Besides gallium, which other elements have since been discovered those were left by Mendeleev in his Periodic Table? (Any two)

Mendeleev predicted the existence of certain elements which were not discovered at that time. He left some gaps in the periodic table for the discovery of new elements such as Eka-aluminium or gallium of group- 13 of the modern periodic table. The other two elements are Eka-silicon which is the germanium of group- 14 and Eka-boron which is the scandium of group- 15 of the modern periodic table.

Which of the following is not a correct statement about the trends when going from left to right across the periods of the Periodic Table?

The atoms lose their valence electrons more easily.

The elements become less metallic in nature.

The number of valence electrons increases.

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 5 - Periodic Classification of Elements>assam board-2019>Q 8

MEDIUM

10th Assam Board

IMPORTANT

Earn 100

The position of elements A, B, and C in the Periodic Table are shown below.

Group 16 Group 17

- -

- -

- A

B C

State whether A is a metal or non-metal.

Important Questions on Periodic Classification of Elements

MEDIUM

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 5 - Periodic Classification of Elements>assam board-2019>Q 9

The position of elements A, B, and C in the Periodic Table are shown below.

Group 16	Group 17
-	-
-	-
-	A
B	C

State whether C is more reactive or less reactive than A.

MEDIUM

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 5 - Periodic Classification of Elements>assam board-2019>Q 10

The position of elements A, B, and C in the Periodic Table are shown below.

Group 16	Group 17
-	-
-	-
-	A
B	C

Will C be larger or smaller in size than B.

MEDIUM

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 5 - Periodic Classification of Elements>assam board-2020>Q 11

An atom has electronic configuration

2, 8, 7

. To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses)

HARD

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 5 - Periodic Classification of Elements>assam board-2020>Q 13

What is Newlands’ Law of Octaves? What were the limitations of Newlands’ Law of Octaves?

HARD

10th Assam Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 5 - Periodic Classification of Elements>assam board-2018>Q 14

Nitrogen (atomic number $7$ ) and phosphorus (atomic number $15$ ) belong to group $15$ of the Periodic Table. Write the electronic configuration of these two elements. Which one of these will be more electronegative? Why?