Q3 of 43 Page 26

The number of electrons in an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?

The mass number of the element is 31. The element can be represented as X 1531 where 31 is the mass number of the element. 15 is the atomic number of the element.

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1

Which of the following correctly represents the electronic distribution in the Mg atom?

 2

Rutherford’s ‘alpha (α) particles scattering experiment’ resulted into discovery of

 4

Dalton’s atomic theory successfully explained

(i) Law of conservation of mass


(ii) Law of constant composition


(iii) Law of radioactivity


(iv) Law of multiple proportions

 5

Which of the following statements about Rutherford’s model of atom are correct?

(i) considered the nucleus as positively charged


(ii) established that the α–particles are four times as heavy as a hydrogen atom


(iii) can be compared to solar system


(iv) was in agreement with Thomson’s model