MEDIUM
10th CBSE
IMPORTANT
Earn 100

Lithium, sodium and potassium from a Dobereiner’s triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Important Questions on Periodic Classification Of Elements

MEDIUM
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 1
Why is there a necessity for the classification of elements? Give at least two reasons.
MEDIUM
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 2
What do you understand by triad of elements? Give an example.
MEDIUM
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 2
State Dobereiner’s law of triads.
HARD
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 3
Cl, Li, Ca, Br, Na,Sr, I, K and Ba. From the list of elements given above make three triads and name the family of each triad,
HARD
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 4
Can the following groups of elements be classified as Dobereiner’s triad?

(a) Na, Si, CI
(b) Be, Mg, Ca
Atomic mass of Be 9; Na 23; Mg 24; Si 28; Cl 35; Ca 40

Explain by giving a reason.
HARD
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 5
The three elements A. B and C with similar properties have atomic masses X. Y and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called?
Give one example of such a set of elements.
HARD
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 1
(j) What is the achievement of Dobereiner’s law of triads?

(ii) What were the reasons for rejecting this classification?
HARD
10th CBSE
IMPORTANT
Core Science Chemistry>Chapter 5 - Periodic Classification Of Elements>EXERCISE 5A>Q 2
(i) State the law of octaves,
(ii) Name the scientist who framed the above law.
(iii) Two elements A and B obey the law of octaves. How many elements are in between A and B?