MEDIUM
9th CBSE
IMPORTANT
Earn 100

Explain the three main postulates of Bohr's model of an atom. 

Important Questions on Structure of Atom

HARD
9th CBSE
IMPORTANT
Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 13
The average atomic mass of a sample of an element 'X' is 16.2 u. What is the percentage of each isotope X816 and X618  in the sample? 
HARD
9th CBSE
IMPORTANT
Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 14

Consider the following table:

Element Atomic number Number of neutrons
A 3 4
B 9 10
C 13 14
D 17 18
E 18 22

(i) How many protons are there in an atom of D?
(ii) What is the mass number of B?
(iii) Write electron distribution of C.
(iv) What is the valency of E?
(v) What is the number of electrons present in a monovalent positive cation of A and a monovalent anion of D?