CBSE Important Questions(Short questions) for Structure of atoms
Given below are the Class 9 Science Extra Questions for CBSE for Structure of atoms. These are important questions also
(a) Very Short Answer type
(b) Short Answer type
(c) Long answer questions
Hope you like them and do not forget to like , social share and comment at the end of the page.
Very Short Answer type
Question 1.
Write the charge and mass of an electron?
Answer
Charge of electron =$1.60 \times 10^{-19}$ coulombs
Mass of electron =$9.11 \times 10^{-31}$ kg
Question 2.
How many electrons at the maximum can be present in the first shell of an atom?
Answer
2
Question 3.
List three subatomic particles of an atom?
Answer
electrons, neutrons and Protons
Question 4.
Name two any two noble gases?
Answer
Helium and Neon
Question 5.
Write the value of charge on electron
Answer
Charge of electron =$1.60 \times 10^{-19}$ coulombs
Question 6.
Define mass number?
Answer
The mass number of an atom is equal to the number of nucleons in its nucleus.
Question 7.
Define atomic number?
Answer
The atomic number of an element is the same as the number of protons in the nucleus of its atom
Question 8.
Write the symbol 18Ar40 , write down the number of neutrons present in the nucleus of the atom?
Answer
number of neutrons=40-18=22
Question 9.
Which has more number of electrons Na or Na+ ? Why?
Answer
Na has more electron them Na+ as +ions depicts electron are removed
Question 10.
Name the particles which determine the mass of an atom?
Answer
neutrons and protons
Question 11.
Who discovered neutron?
Answer
J. Chadwick
Short answer type
Question 1.
Why did Rutherford select a gold foil for his experiment? Question 2.
What are canal rays? Question 3.
Write the symbols of two isotopes of uranium? Question 4.
Write three applications of isotopes in various fields? Question 5.
An atom of element ’X’ has 3 orbits around its nucleus. What is its maximum electron holding capacity? Question 6.
The oxide of aluminium has a chemical formula Al2O3. State the valency of aluminium? Question 7.
Diagrammatically show the electronic distribution of Na+ in its orbit? Question 8.
Name two elements whose isotopes are used in the field of medicine? Question 9.
Chemical properties of all the isotopes of an element are similar. State reason? Question 10.
If Z = 5, what would be the valency of the element? Also name the element? Question 11.
An ion M+3 has 10 electrons and 14 neutrons. Find its atomic number and mass number of M? Question 12.
Magnesium has 12 protons and 12 neutrons. Fid the valency of magnesium?
Long answer type
Question 1.
Helium atom has two electrons in its valence shell but its valency is not two. Explain? Question 2.
Draw a diagram of the Thomson’s model of an atom. Why was it discarded? Question 3.
What are the differences between isotopes and isobars? Question 4.
Compare all proposed models of an atom? Question 5.
Write the conclusions drawn by Rutherford for the following observing during his alpha scattering experiment:
(a)Most of the alpha- particle passed straight through the gold foil.
(b)Some alpha- particles getting deflected from their path.
(c)Very small fraction of alpha- particles getting deflected by 180C. Question 6.
An element is represented as 8X16 Find:
(a)The number of electrons in element X.
(b)Mass number of an element X.
(c)The number of neutrons in element X. Question 7.
With the help of labeled diagram describe in brief the Rutherford’s experiment. Write any three important conclusions drawn from the experiment? Question 8.
The average atomic mass of a sample of element X is 16.2u. What are the percentage of isotopes 8X16 and 8X18 respectively? Question 9.
State the major drawback in Rutherford’s model which helped compensate this drawback? Question 10.
List three differences between electron, proton and neutron? Question 11.
Compare the K and K+ ion on the following parameters:
(a)Number of electrons
(b)Electronic configuration
(c)Atomic structure (energy shells) Question 12.
Give reasons of following:
(a)An atom is electrically neutral.
(b)Ions are more stable than atoms.
(c)Noble gases show low reactivity.
Summary
This Class 9 Extra Questions for Structure of atoms with answers is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.
