Atomic Structure

1. The nucleus of an atom contains (a) protons only (b) proton and electrons (c) nucleus and electrons (d) protons and neutrons
Right Choice: Option D

2. The following is arrangement of elements in order of decreasing number of outter electrons, one of the element s is wrongly placed, which is it? ALUMINUM, CHLORINE, SILICON< MAGNESIUM, SODIUM (a) Chlorine (b) Aluminum (c) Magnesium (d) Sodium
Right Choice: Option D

3. An element X has 127 neutrons and 82 electrons. Its atomic number is (a) 209 (b) 105 (c) 82 (d) 127
Right Choice: Option B

4. An element, E, has the electronic configuration 1S22S23S23P3. The reaction of E with a halogen X can give 9 a) EX3 and EX5 (b) EX3 only (c) EX5 only (d) EX2 and EX3
Right Choice: Option D

5. Two atoms represented as 23592U and 23892U are (a) isomers (b) allotropes (c) Isotopes (d) anomers
Right Choice: Option D

6. A metallic ion X2+ with an inert gas structure contains 18 electrons. How many protons are there in this ion? 9a0 20 (b) 18 (c) 16 (d) 2
Right Choice: Option A

7. Given the mean atomic mass of chlorine prepared in the laboratory to be 35.5 and assuming that chlorine contains two isotopes of mass number 25 and 37. What is the percentage composition of the isotope of mass number 35 ? (a) 20 (b) 24 (c) 50 9d) 75
Right Choice: Option C

8. The postulate of Dalton’s atomic theory which still holds is that (a) particles of different element combine in a simple whole number ratio (b) atoms can neither be created nor destroyed (c) the particles of the same element are exactly alike (d) all elements are made of small indivisible particles
Right Choice: Option C

9. Millikan’s combination to the development of atomic theory is the determination of (a) charge on electron (b) positive rays (c) charge to mass ratio (d) cathode rays
Right Choice: Option C

10. The idea of planetary electrons was that of (a) Bohr (b) Thompson (c) Rutherford (d) Dalton
Right Choice: Option A

EXERCISE

91. Mass of an atom is determined by (a) its ionization potential (b) the number of protons electrons (c) the number of neutrons electrons and protons (d) the number of neutrons and electrons

92. 31R, 199U, 2412S, 2010T, 179Y. Which of the following statement is NOT true of the element R, U, S, T, Y (a) R is an isotope of hydrogen (b) U and Y are isotopes (c) R, U, S and T are metals (d) T is a noble gas

93. A particle that contains 9 protons, 10 neutrons, 10 electrons is a (a) negative ion (b) positive ion (c) neutral atom of a nonmetal (d) neutral atoms of metal

94. The line observed in the simple hydrogen spectrum are due to emission of 9a0 electron from the atom (b) energy by protons transition (c) energy by electron transition (d) neutrons from the atom

95. What is the valence shell electron configuration of the element with atomic number 17? (a) 1S22S22P63S23P5 (b) 1S22S22P63S23P4 (c) 3S23P5 (d) 2S22P6

96. The component of an atom that contributes least to its mass is the (a) nucleus (b) neutron (c) electron (d) proton

97. The shape of the s-orbital is (a) spherical (b) elliptical (c) spiral (d) circular

98. An electron can be added to a halogen atom to form a halide ion with (a) 2 valence electrons (b) 3 valence electrons (c) 7 valence electrons (d) 8 valence electrons

99. Neutral atoms of neon with atomic number 10 have the same number of electrons as (a) )2+(b) Ca2+(c) K+(d) Mg2+

100. The electron configuration of two elements with similar chemical properties are represented by (a) 1S22S22P5 and 1S22S22P4 (b) 1S22S22P5 and 1S22S22P6 3S1 (c) 1S22S22P63S1and 1S22S1 (d) 1S22S22P4 and 1S22S1

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