## Complete the following table.

[question] Question. [/question] [solution] Solution: [/solution]...

## Which one of the following is a correct

[question] Question. Which one of the following is a correct electronic configuration of sodium? (a) 2,8 (b) $8,2,1$ (c) $2,1,8$ (d) $2,8,1$ [/question] [solution] Solution: (d) [/solution]...

## Choose the correct answer :

[question] Question. Choose the correct answer : Number of valence electrons in $\mathrm{Cl}^{-}$ion are (a) 16 (b) 8 (c) 17 (d) 18 [/question] [solution] Solution: (b) [/solution]...

## Choose the correct answer :

[question] Question. Choose the correct answer : Isotopes of an element have (a) The same physical properties (b) Different chemical properties (c) Different number of neutrons (d) Different atomic numbers [/question] [solution] Solution: (c) [/solution]...

## Choose the correct answer :

[question] Question. Choose the correct answer : Rutherford’s alpha-particle scattering experiment was responsible for the discovery of (a) Atomic nucleus (b) Electron (c) Proton (d) Neutron [/question] [solution] Solution: (a) [/solution]...

## For the following statements,

[question] Question. For the following statements, write T for ‘True’ and F for ‘False’. (a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons. (b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral. (c) The mass of an electron is about $\frac{1}{2000}$ times that of proton. (d) An isotope of iodine is used for making tincture iodine, which is used as a medicine. [/question] [solution] Solution: (a) (F) (b) (F) (c) (T) (d) (F) [/so...

## Composition of the nuclei of two atomic

[question] Question. Composition of the nuclei of two atomic species X and Y are given as under Give the mass numbers of X and Y. What is the relation between the two species? [question] [solution] Solution: Mass number of X = Number of protons + Number of neutrons = 6 + 6 = 12 Mass number of Y = Number of protons + Number of neutrons = 6 + 8 = 14 These two atomic species X and Y have the same atomic number, but different mass numbers. Hence, they are isotopes. [/solution]...

## If Z = 3, what would be the valency of the element?

[question] Question. If Z = 3, what would be the valency of the element? Also, name the element. [/question] [solution] Solution: By Z = 3, we mean that the atomic number of the element is 3. Its electronic configuration is 2, 1. Hence, the valency of the element is 1 (since the outermost shell has only one electron). Therefore, the element with Z = 3 is lithium. [/solution]...

## For the symbol H

[question] Question. For the symbol H, D and T tabulate three sub-atomic particles found in each of them. [/question] [solution] Solution: [/solution]...

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