Question

(1) How many elements are known presently ?

(A) 118 (B) 114 (C) 128 (D) 108

(2) Which scientist classified elements into triads ?

(A) John Newland (B) Wolfgang Dobereiner (C) Mendeleev (D) Lother Mayer


(3) What is indicated by pairs of following elements ?

(i) Li, Na, K (ii) Ca, Sr, Ba (iii) Cl, Br, I

(A) increasing order of atomic mass (B) Dobereiner’s triads

(C) increasing order of atomic number (D) Octaves


(4) Who gave “law of octaves” ?

(A) Mendeleev (B) Kankortois (C) Lother Mayer (D) John Newland


(5) What was the limitation of Dobereiner for classification of elements ?

(A) He could only make three traids

(B) He could make only five triads

(C) It had no relation with atomic mass of elements.

(D) The properties of elements can not be predicted by them.


(6) Scientist John Newland arranged elements in increasing order of .........

(A) Atomic number (B) Atomic mass

(C) Physical properties (D) Chemical properties


(7) What name did Mendeleev give to Eka-Aluminium element ?

(A) Galium (B) Germanium (C) Scandium (D) Nobelium


(8) What is the limitation of octave principle ?

(A) It applies till calcium only

(B) He kept two elements at one place to elements.

(C) Octave principles apply to lighter elements

(D) All of the above​

Answer 1

ANSWERS

(1) How many elements are known presently ?

Ans :-  (A) 118

(2) Which scientist classified elements into triads ?

 Ans:-  (B) Wolfgang Dobereiner

(3) What is indicated by pairs of following elements ?

Ans :- (B) Dobereiner’s triads

(4) Who gave “law of octaves” ?

Ans :-  (D) John Newland

(5) What was the limitation of Dobereiner for classification of elements ?

Ans :-  (A) He could only make three traids

(6) Scientist John Newland arranged elements in increasing order of

Ans :- (B) Atomic mass

(7) What name did Mendeleev give to Eka - Aluminium element ?

Ans:- (A) Gallium

$\red\bigstar$ Actually Mendeleev called the element Eka - Aluminium and now it is known as Gallium.

(8) What is the limitation of octave principle ?

Ans:- (D) All of the above​

Answer 2

1)a)118

2)b)Wolfgang Dobereiner

3)b)Dobereiner's traid

4)d)John Newland

5)c)it had no relation with atomic mass of elements

6)b)Atomic mass

7)a)Galium

8)d)all of the above