Chemistry - 9 Chapter - 4Periodicity of Elements and Periodic TableTest - 2

Chemistry - 9 Chapter - 4
Periodicity of Elements and Periodic Table
Test - 2

1. Dobereiner was a ______.

a) British
b) German
c) American
d) Indian

2. Elements with similar properties were grouped in "Triads" by ?

a) Lother Meyer
b) Newland
c) Mendeleef
d) Dobereiner

3. Find out atomic mass of Na in a triads Li=7, Na=?, Ka=39?

a) 19
b) 23
c) 46
d) 32

4. Find out atomic mass of Sr in triads Ca = 40, Sr ?, Ba = 137 ?

a) 58.8
b) 88
c) 88.8
d) 85

5. Formula to find out atomic mass of Br in triads Cl=35, Br=?, I=127 ?

a) 35+127/2
b) 127/2
c) 35+127*2
d) 35/2

6. How average mass in Doberiener's group of 3 called triads is calculated? ( Pick the wrong statement )

a) Atomic masses of three elements written in a row as (7, 23, 39) (Li, Na and K).
b) Atomic mass of central element equal to the average mass of the other two i.e. (38 + 8) / 2 = 23
c) Atomic mass of central element equal to the average mass of the other two i.e. (39 + 7) / 2 = 23

7. What do you understand by word triad? Triad means a group of three people or things.

a) Triad means a group of three people or things.
b) Triad means a group of two people or things.
c) Triad means a group of five people or things.
d) Triad means a group of four people or things.

8. In "Triads" the atomic mass of second element is equal to average mass of _________?

a) First and second element
b) Second and their element
c) No answer is correct
d) First and their element

9. In the beginning elements were grouped based on their physical state at high temperature as solid, liquid and gas and as metals and non metals.

a) True
b) False

10. What was the drawback in arranging elements according to Doberiener's group of 3 called triads? Short..Answer..........................................................
and

a) C. It was difficult to obtain an overall picture of a large number of elements.
b) D. it was difficult to see the picture of number of elements.
c) A. Very less elements could be arranged in these manners.
d) B. A and C are correct

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