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 do you think would be the observation if the ?-particle scattering experiment is carried out using a foil of a metal other than gold?
Q 2.
Who discovered protons?
Q 3.
Fill in the blanks :
In the three fundamental sub-atomic particles, _________ are negatively charged, _________ are positively charged and ____________ have no charges.
Q 4.
If an atom contains one electron and one proton, will it carry any charge or not?
Q 5.
Describe briefly Thomson's model of an atom.
Q 6.
Fill in the blanks :
Anode rays are also called ___________.
Q 7.
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 8.
On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?
Q 9.
Compare an electron, a proton and a neutron in respect of their relative masses and charges.
Q 10.
What is mass number?
Q 11.
Write a short note on Nucleus.
Q 12.
What is the absolute mass and charge of a proton ?
Q 13.
What is the maximum number of electrons an M shell of the atom can accommodate ?
Q 14.
What is the maximum number of electrons which can be accommodated in the L shell of an atom
Q 15.
State the number of electrons present in the outermost shell of the atoms of the following elements :
(i) Neon(ii)Chlorine
Q 16.
Give one use each of the following radioactive isotopes :
(a)Uranium-235 (b) Cobalt-60
Q 17.
How many times is a proton heavier than an electron ?
Q 18.
Who discovered electrons?
Q 19.
What is ionization energy?
Q 20.
Fill in the blanks :
Rutherford's scattering experiment is related to to the size of ____________.
Q 21.
If A = 23 and Z = 11 for Na atom, how many protons, electrons and neutrons present in Na atom?
Q 22.
What were the important features of atomic model based on Rutherford's scattering experiment?
Q 23.
What is a neutron ? State its relative mass and charge.
Q 24.
Fill in the blanks :
The maximum number of electrons that can be accommodated in L-shell are _______.
Q 25.
Fill in the blanks :
Atoms are made up of __________, ___________ and __________.
Q 26.
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 | ........ | ....... | ........ | ......... |
Q 27.
Who discovered neutrons?
Q 28.
What are ?-particles?
Q 29.
Fill in the blanks :
______ are atoms of the same element, which have same number of protons but different mass numbers.
Q 30.
State the location of electrons, protons and neutrons in an atom.
Q 31.
What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons ?
Q 32.
Fill in the following blanks
Atomic
number | Mass number | Protons | Neutrons | Electrons | Symbol |
|---|
| 10 | 22 | ....... | ........ | ....... | ........ |
Q 33.
Fill in the blanks :
The mass number of an atom is equal to the number of ________ in its nucleus.
Q 34.
What is the electronic configuration of a hydrogen atom
Q 35.
What are the limitations of Rutherford’s model of the atom?
Q 36.
Which part of an atom was discovered by Rutherford's alpha particle scattering experiment ?
Q 37.
Which radioactive isotope is used to determine the activity of thyroid gland ?
Q 38.
Which of the following are isotopes and which are isobars ?
Argon, Deuterium, Calcium, Tritium, Protium
Q 39.
Complete the following table.
| Particle | Electron | Proton | Neutron |
|---|
| (i) Symbol | __ | __ | __ |
| (ii) Nature | __ | __ | __ |
| (iii) Relative Charge | __ | __ | __ |
| (iv) Absolute Charge | __ | __ | __ |
| (v) Relative Mass | __ | __ | __ |
| (vi) Absolute Mass | __ | __ | __ |
Q 40.
Draw a sketch of Bohr’s model of an atom with three shells.
Q 41.
Name the positively charged particle present in the atoms of all the element
Q 42.
How does a proton differ from an electron ?
Q 43.
How does an electron differ from a neutron ?
Q 44.
State one use of radioactive isotopes in medicine.
Q 45.
Name the radioactive isotope which is used in the treatment of cancer.
Q 46.
State one use of radioactive isotopes in industry.
Q 47.
What name is given to those isotopes which have unstable nuclei and emit various types of radiations ?
Q 48.
(a)What are valence electrons ? Where are valence electrons situated in an atom ?
(b)What is the number of valence electrons in the atoms of an element having atomic number 13 ? Name the Valency shell of this atom.
Q 49.
Who discovered nucleus of an atom?
Q 50.
What is the mass of proton as compared to electron?
