Page 1 - 2. HA- Obj & Sub Ch-5 CLASSIFICATION BY DOB.& NEWL.

SAI International School
Class-X

Subject_ Chemistry
Topic- Periodic Classification
Sub topic- Dobereiner’s Classification & Newland's Law of Octave

Home Assignment

Objective -
Q.1 If the two members of a Dobereiner triad are phosphorus and
antimony, the third member of this triad is-

(a) arsenic (b) sulphur
(c) iodine (d) calcium
Q.2
Cl, Br, I, if this is Dobereiner’s triad and the atomic masses of Cl and I are
35.5 and 127 respectively the atomic mass of Br is-
(a) 162.5 (b) 91.5
(c) 81.25 (d) 45.625

Q.3
Newland could classify elements only upto-
(a) copper (b) chlorine
(c) calcium (d) chromium

➢ For Assertion& Reason question follow the following directions.

DIRECTION: Each of these questions contains an Assertion followed by Reason. Read
them carefully and answer the question on the basis of following options. You have to
select the one that best describes the two statements.

(a) If both Assertion and Reason are correct and Reason is the correct explanation of
Assertion.

(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of
Assertion.
(c) If Assertion is correct but Reason is incorrect.

(d) If Assertion is incorrect but Reason is correct.

(e) If Assertion & Reason both are incorrect.

Q.4 Assertion: In a triad, the three elements have same gaps of atomic masses.
Reason: Elements in a triad have similar properties.

Q.5
Assertion : Be, Mg and Ca can be classified as Dobereiner’s triads.
Reason : Atomic mass of Mg is approximately the average of the sum of
atomic masses of Be and Ca.

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