Atoms of the same element, but of different masses are called__________________?

Related Mcqs:

1. Equal masses of CH4 and H2 are mixed in an empty container. The partial pressure of hydrogen in this container expressed as the fraction of total pressure is___________________?

   A. 1/9
   B. 8/9
   C. 1/2
   D. 5/9

2. What is the simplest formula of a compound containing 50% of element A (atomic weight = 10) and 50% of element B (atomic weight = 20) ?

   A. AB3
   B. A2B3
   C. A2B
   D. AB2

3. A sample of well water contains 140 gm/m3 Ca2+ ions and 345 gm/m3 Na+ ions. The hardness of the sample of water, expressed in terms of equivalent CaCO3 in gm/m3 is (assuming atomic masses of Ca :40, Na : 23, C : 12, O : 16) ?

   A. 350
   B. 485
   C. 140
   D. 345

4. “The rate at which a substance reacts is proportional to its active mass and the rate of a chemical reaction is proportional to the product of active masses of the reacting substances”. This is the_________________?

   A. Lewis-Randall rule
   B. Statement of Van’t Hoff Equation
   C. Le-Chatelier’s principle
   D. None of these

5. Isotopes are atoms having the same _____________________?

   A. Mass number
   B. Number of neutrons
   C. Atomic mass
   D. None of these

6. The total number of atoms in 8.5 gm of NH3 is _______________ × 1023?

   A. 9.03
   B. 3.01
   C. 1.204
   D. 6.02

7. In an amorphous material, atoms defy any definite atomic structure and exist in random pattern just like in liquid. Which of the following is an amorphous material ?

   A. Tin
   B. Lead
   C. Zinc
   D. Glass

8. There are one octahedral void and ______________ tetrahedral void in the closest packing of atoms ?

   A. One
   B. Two
   C. Three
   D. None of these

9. Neutrons are present in all atoms except that of ___________________?

   A. He
   B. C
   C. H
   D. Ar

10. The number of atoms of oxygen present in 11.2 litres of ozone (O3) at N.T.P. are__________________?

    A. 3.01 × 1022
    B. 6.02 × 1023
    C. 9.03 × 1024
    D. 1.20 × 1024