$(a)$ An ion $M^{2+}$ contains $10$ electrons and $12$ neutrons. What is the atomic number and mass number of the element $M$?
$(b)$ Is it possible in an atom to have $12$ protons and $13$ electrons? Explain.
$(c)$ Why is helium gas inert?

  • A
    $(a)$ Atomic number $= 12$,Mass number $= 24$
  • B
    $(b)$ No,it is not possible
  • C
    $(c)$ Helium has a completely filled outermost shell
  • D
    $(d)$ All of the above

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Similar Questions

Name any two noble gases.

Dalton's atomic theory successfully explained which of the following laws?
$(i)$ Law of conservation of mass
$(ii)$ Law of constant composition
$(iii)$ Law of radioactivity
$(iv)$ Law of multiple proportion

$(a)$ Explain why did Rutherford select a gold foil in his alpha scattering experiments?
$(b)$ What observations in $\alpha$-scattering experiment led Rutherford to make the following conclusions?
$(i)$ Most of the space in an atom is empty.
$(ii)$ Nucleus is positively charged.
$(c)$ Mention any two drawbacks of Rutherford's model.

Rutherford's $\alpha-$ particle scattering experiment showed that
$(i)$ Electrons have negative charge
$(ii)$ The mass and positive charge of the atom is concentrated in the nucleus
$(iii)$ Neutron exists in the nucleus
$(iv)$ Most of the space in atom is empty
Which of the above statements are correct?

In a sample of ethyl ethanoate $(CH_3COOC_2H_5)$,the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for it?

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