Question:
What is mass number?
Answer:
Mass number (A) is equal to number of nucleons present inside the nucleus. It
means it is the sum of number of protons and neutrons present in the nucleus of an atom. It is
denoted by letter A.
Structure of the Atom
Q 1.
What were the important features of atomic model based on Rutherford's scattering experiment?
Q 2.
What are cathode rays?
Q 3.
Who discovered electrons?
Q 4.
If A = 23 and Z = 11 for Na atom, how many protons, electrons and neutrons present in Na atom?
Q 5.
Who discovered protons?
Q 6.
Write the limitations of J.J. Thomson's model of an atom.
Q 7.
Fill in the blanks :
The total number of protons and neutrons in the nucleus of an atom is called its __________.
Q 8.
Fill in the blanks :
Rutherford's scattering experiment is related to to the size of ____________.
Q 9.
What is the mass of proton as compared to electron?
Q 10.
Fill in the blanks :
The mass number of an atom is equal to the number of ________ in its nucleus.
Q 11.
Fill in the blanks :
An atom has mass number 27 and atomic number 13. The atom has _________ electrons, _____ protons and _______ neutrons.
Q 12.
Who discovered neutrons?
Q 13.
Fill in the blanks :
The maximum number of electrons that can be accommodated in K-shell are _______.
Q 14.
What are ?-particles?
Q 15.
Fill in the blanks :
The fundamental sub-atomic particle called neutron was discovered by ___________.
Q 16.
Name the fundamental particle not present in the nucleus of hydrogen atom
Q 17.
Fill in the blanks :
The _________ of an atom is dense, small in size and is positively charged.
Q 18.
Fill in the blanks :
Mass of a proton is __________ times the mass of an electron.
Q 19.
If an atom contains one electron and one proton, will it carry any charge or not?
Q 20.
On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?
Q 21.
Fill in the blanks :
The maximum number of electrons that can be accommodated in L-shell are _______.
Q 22.
State the number of electrons present in the outermost shell of the atoms of the following elements :
(i) Neon(ii)Chlorine
Q 23.
Who discovered X-Rays?
Q 24.
What name is given to the pair of atoms such as
N and
N ?
Q 25.
What are the limitations of Rutherford’s model of the atom?
Q 26.
What is mass number?
Q 27.
State the location of electrons, protons and neutrons in an atom.
Q 28.
(a) Describe the Rutherford's model of an atom. State one drawback of Rutherford's model of the atom.
(b) The mass number of an element is 23 and it contains 11 electrons. What is the number of protons and neutrons in it ? What is the atomic number of the element ?
Q 29.
Fill in the blanks :
Anode rays are also called ___________.
Q 30.
Fill in the following blanks
Atomic
number | Mass number | Protons | Neutrons | Electrons | Symbol |
|---|
| 10 | 22 | ....... | ........ | ....... | ........ |
Q 31.
Name the radioactive isotope which is used in the treatment of cancer.
Q 32.
What name is given to those isotopes which have unstable nuclei and emit various types of radiations ?
Q 33.
What are the properties of anode rays?
Q 34.
Describe briefly Thomson's model of an atom.
Q 35.
Who is known as 'Father of Nucleus Physics'?
Q 36.
What were the observations of Rutherford's ?-scattering experiment?
Q 37.
Which shell of an atom can accommodate a maximum of
(a) 8 electrons?
Q 38.
State one use of radioactive isotopes in industry.
Q 39.
What are isobars ? Explain with an example.
Q 40.
Name the scientist who discovered electron.
Q 41.
Name the particles which actually determine the mass of an atom.
Q 42.
Name the positively charged particle present in the atoms of all the element
Q 43.
Which part of an atom was discovered by Rutherford's alpha particle scattering experiment ?
Q 44.
What is the positive charge on the nucleus of an atom due to ?
Q 45.
Name the shell of an atom which can accommodate a maximum of
(a) 2 electrons (b) 18 electrons
Q 46.
The total number of electrons in a nitrogen atom is 7. Find the number of valence electrons in it.
Q 47.
Give one example of a radioactive isotope which is used as a fuel in the reactors of nuclear power plants.
Q 48.
State whether the following statement is true or false :
Radioactive isotope of iodine is used for making the medicine called tincture iodine.
Q 49.
What is the relationship between an atom containing 11 protons, 11 electrons and 11 neutrons, and another atom containing 11 protons, 11 electrons and 12 neutrons ?
Q 50.
Fill in the following blanks in respect of an atom of an element :
No.of
protons | No.of
neutrons | Mass number | Atomic
number | No.of
electrons | Valency |
|---|
| 11 | 12 | ........ | ....... | ........ | ......... |
