XI Chemistry Unit 3 Part 3

In Chancourtois concept, one complete turn of a helix corresponds to an atomic weight increase of _____.

• 18

• 16

• 14

• 12

Match the list-I and list-II using the code given below the list.

List-I - List-II

A. Law of triads - 1. Chancourtois

B. Law of octaves - 2. Henry Moseley

C. First periodic law - 3. Newland

D. Modem periodic law - 4. Johann Dobereiner

• 4 3 1 2

• 3 4 2 1

• 1 3 4 2

• 2 3 1 4

Which of the following elements were unknown at that time of Mendeleev?

• Na, Mg

• Fe, Co

• K, Cu

• Ga, Ge

What is the general electronic configuration of alkali metals?

• ns¹

• ns²

• ns² np⁶

• ns² np⁵

Modern periodic table contains _____ groups and _____ periods.

• 2,8

• 7,18

• 18,7

• 20,5

Which of the following does not belongs to Group – I element ?

• Na

• K

• Cs

• He

_____ provides a theoretical foundation for the modern periodic table.

• Hund’s rule and Aufbau principle

• Aufbau principle and Electronic configuration

• Quantum numbers

• Hund’s rule and electronic configuration

In Mosley’s graph, we can determine the _____ of an unknown (new) element from the frequency of X – ray emitted.

• atomic number

• atomic weight

• electronic configuration

• energy

The repetition of physical and chemical properties of elements at regular intervals is called _____.

• atomicity

• periodicity

• aromaticity

• energy level

The groups of periodic table are numbered by _____.

• National Chemical Laboratory

• IUPAC

• American Chemical Society

• Element Naming Agency