Q27. Number of valence electrons in Cl– ion are:

(a) 16 (b) 8 (c) 17 (d) 18

 

Q28. Write down the electron distribution of chlorine atom. How many electrons are there in the L shell? (Atomic number of chlorine is 17)

 

Q29. Which of the following statements about Rutherford’s model of atom are correct?

(i)    Considered the nucleus as positively charged.

(ii)   Established that the a-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.

(a) (i) and (iii)     (b) (ii) and (iii)     (c) (i) and (iv)     (d) Only (i)

 

Q30. In response to a question, a student stated that in an atom, the number of protons is greater than the number of neutrons, which in turn is greater than the number of electrons. Do you agree with the statement? Justify your answer.

 

Q31. Will 35Cl and 37Cl have different valencies? Justify your answer.

 

Q32. 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 1/2000 times that of proton.

(d) An isotope of iodine is used for making tincture iodine, which is used as a medicine. 

 

Q33. Fill in the blanks in the following statements.

(a) Rutherford’s a-particle scattering experiment led to the discovery of the_____.

(b) Isotopes have same ______ but different ______.

(c) Neon and chlorine have atomic numbers 10 and 17 respectively. Their valencies will be______ and _______ respectively.

(d) The electronic configuration of silicon is _____ and that of sulphur is______.

 

Q34. For the symbol H, D and T tabulate three sub-atomic particles found in each of them.

 

Q35. Draw a sketch of Bohr’s model of an atom with three shells.

 

Q36. What are canal rays?

 

Q37. Na+ has completely filled K and L shells. Explain.

 

Q38. Helium atom has 2 electrons in its valence shell but its valency is not 2. Explain.

 

Q39. On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole.

 

Q40. Find out the valency of the atoms represented by the Fig. (a) and (b).


 

Q41. In a sample of ethyl ethanoate (CH3COOC2H5) 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? 

(a) One of the oxygen atoms has gained electrons.

(b) One of the oxygen atoms has gained two neutrons.

(c) The two oxygen atoms are isotopes.

(d) The two oxygen atoms are isobars.

 

Q42. Why do Helium, Neon and Argon have a zero valency?

 

Q43. Composition of the nuclei of two atomic species X and Y are given as under

 

 

X

Y

Protons

=

6

6

Neutrons

=

6

8

 

Give the mass numbers of X and Y. What is the relation between the two species?

 

Q44. An element X has a mass number 4 and atomic number 2. Write the valency of this element?

 

Q45. The average atomic mass of a sample of an element X is 16.2 u.

What are the percentages of isotopes   and   in the sample?

 

Last modified: Tuesday, 1 June 2021, 6:45 PM