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Standard VII

Chemistry

Mass Number

Question: The...

Question

Question:
The ratio of atomic numbers of P and Q is 1:2. The number of electrons present in the valence shell M of P is equal to the difference in the number present in its other two shells.What is the atomic number of Q?
{I request the experts to solve the question with apt explanation}

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Solution

Dear student,

The number of electrons present in K shell is 2.
The number of electrons present in L shell is 8.

The difference of electrons present in K and L shells is, 2-8=6.

Therefore, the number of electrons present is M shell is 6.
Hence, the atomic number of P is 16.

The ratio of P and Q is 1:2.
Therefore, the atomic number of Q is 2 x 16 = 32

Hence, the atomic number of Q is 32.

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Multiple Choice Questions

(a) The outermost shell of an atom is known as

(i) valency

(ii) valence electrons

(iii) nucleus

(iv) valence shell

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(i) two

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(iii) four

(iv) five

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(iii) 18

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(e) The number of electrons in an atom is equal to the number of

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(iii) nucleons in a neutral atom

(iv) none of the above

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(iii) number of electrons

(iv) all of the above

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Q. The total number of electrons present in first two and last two shells is the same for an atom of an element X.The sum of the electrons present in second, fourth and fifth shells is equal to the number of electrons present in third shell and fifth shell is valence shell. To which group in the periodic table would it belong?

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Question: The ratio of atomic numbers of P and Q is 1:2. The number of electrons present in the valence shell M of P is equal to the difference in the number present in its other two shells.What is the atomic number of Q? {I request the experts to solve the question with apt explanation}

Question:
The ratio of atomic numbers of P and Q is 1:2. The number of electrons present in the valence shell M of P is equal to the difference in the number present in its other two shells.What is the atomic number of Q?
{I request the experts to solve the question with apt explanation}