Atoms and Molecules-MCQ

1.  The atomicity of K₂Cr₂O₇ is

        I.  9

       II.  11

      III.  10

      IV.  12

2.  The formula for quicklime is

        I.  CaCl₂

       II.  CaCo₃

      III.  Ca(OH)₂

      IV.  CaO

3.  The symbol of cadmium is

        I.  Ca

       II.  Cu

      III.  Cm

      IV.  Cd

4.  All noble gas molecules are

        I.  Monoatomic

       II.  Diatomic

      III.  Triatomic

      IV.  Both I and II

5.  The valency of nitrogen in NH3 is

        I.  1

       II.  3

      III.  4

      IV.  5

6.  The formula of ethanol is C₂H₅ – OH. What will be its molecular mass?

        I.  46 u

       II.  34 u

      III.  34 g

      IV.  46 g

7.  Number of moles present in 28g of nitrogen atoms are

        I.  1 mole

       II.  2.3 moles

      III.  0.5 mole

      IV.  2 moles

8.  The molecular mass of x is 106. x can be

        I.  CaCo₃

       II.  So₃

      III.  Na₂Co₃

      IV.  NaCl

9.  Which among the following is not a postulate of Dalton�s atomic theory?

        I.  Atoms can not be created or destroyed

       II.  Atoms of different elements have different sizes, masses and chemical properties

      III.  Atoms of same elements can combine in only one ratio to produce more than any one compound

      IV.  Atoms are very tiny particles which can not be further divided

10.  Which of the following is a wrong Combination?

        I.  6.022 * 10²³ molecules of oxygen = 32g of oxygen

       II.  6.022 * 10²³ ions of sodium = 23g of sodium

      III.  6.022 * 10²³atoms of C = 24g of carbon

      IV.  6.022 * 10²³ atoms of H = 1g of hydrogen atoms