statements are thue (d) All of these (e) None of these statements are true. 2. W
ID: 576414 • Letter: S
Question
statements are thue (d) All of these (e) None of these statements are true. 2. Which of the following postulates of Dalton's atomic theory is/are still valid today? (I) Matter consists of particles called atoms. (II) Atoms are indestructible and indivisible. (III) All atoms of an element are identical. (IV) Atoms of different elements differ in mass. (V) When the atoms of different elements combine to form compounds they combine in simple whole number ratios. (a) All of these statements are still valid today. (b) I and II are still valid, but not III, IV and V. (c) I, II and III are still valid, but not IV and V (d) I, IV and V are still valid, but not II and III. (e) II and III are still valid, but not I, IV and V. 3. Calculate the number of protons in the average potassium atom if the atomic weight of potassium is 39 amu and the atomic number of this element is 19. ) 20 (c) 39 (d) 58 (e) The number of protons is impossible to determine from this information. Which statement correctly describes the difference between the 12C, 13C and 14C isotopes of carbon? 4. (a) They have the same number of protons but different numbers of electrons. (b) They have the same number of neutrons but different numbers of electrons. (c) They have the same number of electrons but different numbers of protons. (d) They have the same number of protons but different numbers of neutrons.Explanation / Answer
(2)
(d) I, IV and V are valid but not II and III
* All atoms of an element are not identical. Because elements can have isotopes which differ in their mass number.
* Atoms are divisable. It is made up of mainly three particles called electron, proton and neutron.
4.
(d)
They are isotopes to one other.
So, they have same atomic number ( number of protons ) but differ in their number of neutrons.
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