Available Answers

1. 1.

   Complete the statements given below - by filling in the blanks with the correct word/s from the word/s in bracket.

   1. The word 'atom' is a Greek word meaning ________________ (divisible/indivisible).
   2. The initial contribution towards development of the atomic theory went to Indian & Greek philosophers & later to ____________ (Bohr/John Dalton)
   3. The main postulates of Dalton's atomic theory are-
      1. Matter consits of small particles called ______________ (atoms/ions).
      2. Atoms are ____________ (indivisble/divisible) and ______________ (can/cannot) be created or destroyed.
      3. Atoms of _____________ (different/same) elements are alike, but differ from atoms of other elements.
      4. Compounds or _____________ (mixtures/ions/molecules) are formed when atoms combine with other atoms - in simple whole number ratios.
   4. Contradictios of Dalton's atomic theory by the - Modern Atomic Theory.
      As per the Modern Atomic Theory -
      1. Atoms are __________________ (indestructible/destructible).
      2. Atoms are ___________ (divisible/indivisible).
      3. Atoms consist of subatomic particles generally called _______________, ______________ and ____________ (nucleons/neutrons/neutrinos/positrons/electrons/photons/protons).
      4. Atoms of the same element may not be alike as seen in case of ___________ (isorus/isotopes).
2. 2.

   Select the correct answer from 'A' & 'B' for each of the following statements - pertaining to the experimental discovery of the - subatomic particles.

   1. William Crookes experimental study of cathode rays led to the discovery of - 
      1. Protons
      2. Electrons
   2. Cathode rays were emitted from the -
      1. Negative plate
      2. Positive plate - on passage of electric discharge
   3. J. J. Thompson studied the cathode rays & saw that they were deflected by a - positively charged plate. He concluded that since an atom is electrically neutral - it must contain oppositely charged particles leading to the discovery of -
      1. Neutrons
      2. Protons
   4. Goldstein used a modified cathode ray tube and obtained a new type of rays called - 
      1. Cathode rays
      2. Anode rays
   5. The above rays, consistedof charged particles now called -
      1. Protons
      2. Electrons
   6. Lord Rutherford studies the atomic model leading to the discovery of the -
      1. Orbits or shells of an atom
      2. Atomic nucleus
   7. John Chadwick studied the atomic nucleus leading to the discovery of -
      1. Neutrons
      2. Nucleus
   8. He proved that in the nucleus of the atom are present - particles which have - 
      1. A positive charge, but mass almost equal to the mass of the electron.
      2. No charge, but mass almost equal to the mass of the proton.
   9. Bohr studied the location & mode of rotation of - electrons around the nucleus -
      Postulates of Bohr's atomic theory, included that -
      1. Electrons revolve around the nucleus in - fixed orbits called - energy levels K, L, M, N...
      2. Electrons revolve around the nucleus in - random imaginary paths.
3. 3.

   Complete the table given below by filling in the blank/s - with the correct names.

   

4. 4.

   Select the correct answer from 'A' or 'B' - for each of the statements given below - pertaining to - atomic number & mass number.

   1. Atomic number of an atom [element] - [Z] is equal to - 
      1. Number of protons - in the atom of an element.
      2. Number of neutrons - in the atom of an element.
   2. Atoms are electrically neutral - hence
      1. Number of protons - is equal to the number of neutrons.
      2. Number of electrons - is equal to the number of protons.
   3. Atomic number [Z] is represented as -
      1. Z = p + e
      2. Z = p - e   [p = protons, e = electrons]
   4. Mass number of an atom [element] - [A] is equal to -
      1. Total number of electrons & protons - in the atom of an element.
      2. Total number of neutrons & protons - in the atom of an element.
   5. Mass number [A] is represented as - 
      1. A = p - n
      2. A = p + n
   6. An atom 'X' has mass number 23 & electronic configuration 2, 8, 1.
      It has in it atom
      1. 12 protons
      2. 12 neutrons
   7. An atom 'Y' has 10 electrons & 10 neutrons, its mass number is - 
      1. 20
      2. 19
5. 5.

   Fill in the blanks with correct word/s from the bracket - to complete each statement.

   1. Mass of an atom determined by indirect methods is found to be - very small & hence they are taken in comparison with particles such as _____________ or later ______________ - as the standard for comparison. [oxygen/carbon/nitrogen/hydrogen]
   2. Relative atomic mass - is equal to - the number of times one _________________ [atom/ion/molecule] of the substance - is heavier than - the mass of an atom of ________ or ¹/₁₂ the mass of an - atom of ____________ [nitrogen/carbon/oxygen/hydrogen]
6. 6.

   Electrons revolve around the nucleus in imagindary paths called orbits or shells. Complete the table given below with reference to the diagram given.

   

   1. The maximum number of electrons in each shell is ________________________ [where n is the number of the shell]
   2. The manimum number of electrons in 
      K shell = 2n² = 2 x 12 = __________ electrons
      L shell = 2n2 = ________ = __________ electrons
      M shell = 2n2 = ________ = __________ electrons
   3. An atom has atomic number - 13.
      Its electronic configuration is - _______________ [2, 9, 2/2, 8, 3/2, 8, 4]
   4. An atom has mass number 40 and 18 protons in its nucleus.
      Its electronic configuration is - ________________ [2, 8, 8/2, 9, 7/2, 8, 8, 1]