32 A 32 B 33 A 33 B 33 C 34 A 34 B 34 C 35 A 35 B

Lakhmir Singh & Manjit Kaur - Chemistry

Very Short Answer Type Questions-Pg-191

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28 29 30 31 32 33 34 A 34 B 35 36 37 38 39 40 41 A 41 B 42 43 44 45 46 47 48 49 50 51 52 53

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54 A 54 B 54 C 55 A 55 B 56 A 56 B 57 A 57 B 58 A 58 B 58 C

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Long Answer Type Questions-Pg-211

32 A 32 B 33 A 33 B 33 C 34 A 34 B 34 C 35 A 35 B

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Q. 34 C4.0( 9 Votes )

An element Z contains two naturally occurring isotopes . If the average atomic mass of this element be 35.5 u, calculate the percentage of two isotopes.

Class 9th Lakhmir Singh & Manjit Kaur - Chemistry 4. Structure of Atom

Answer :

Given, Average atomic mass = 35.5 u

Let % amount of ³⁵Z₁₇ be y, then amount of ³⁷Z₁₇ is (100 - y).

So,

So, 35y + 3700 – 37y = 3550

Hence, y = 75

Thus, amount of ³⁵Z₁₇ is 75% and amount of ³⁷Z₁₇ is 25%

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