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.
Compare an electron, a proton and a neutron in respect of their relative masses and charges.
Q 3.
Describe briefly Thomson's model of an atom.
Q 4.
Fill in the blanks :
Anode rays are also called ___________.
Q 5.
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 6.
Fill in the blanks :
In the three fundamental sub-atomic particles, _________ are negatively charged, _________ are positively charged and ____________ have no charges.
Q 7.
Who discovered protons?
Q 8.
What is the absolute mass and charge of a proton ?
Q 9.
How many times is a proton heavier than an electron ?
Q 10.
On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?
Q 11.
What is the maximum number of electrons which can be accommodated in the L shell of an atom
Q 12.
State the number of electrons present in the outermost shell of the atoms of the following elements :
(i) Neon(ii)Chlorine
Q 13.
Give one use each of the following radioactive isotopes :
(a)Uranium-235 (b) Cobalt-60
Q 14.
What is the maximum number of electrons an M shell of the atom can accommodate ?
Q 15.
What is ionization energy?
Q 16.
What is mass number?
Q 17.
If an atom contains one electron and one proton, will it carry any charge or not?
Q 18.
What is a neutron ? State its relative mass and charge.
Q 19.
Fill in the blanks :
Atoms are made up of __________, ___________ and __________.
Q 20.
Fill in the blanks :
______ are atoms of the same element, which have same number of protons but different mass numbers.
Q 21.
Fill in the blanks :
The maximum number of electrons that can be accommodated in L-shell are _______.
Q 22.
Write a short note on Nucleus.
Q 23.
What are ?-particles?
Q 24.
Name the radioactive isotope which is used in the treatment of cancer.
Q 25.
Who discovered electrons?
Q 26.
Fill in the blanks :
Atomic number is equal to _____________.
Q 27.
How does an electron differ from a neutron ?
Q 28.
State one use of radioactive isotopes in medicine.
Q 29.
What is Atomic Number? Who coined this term?
Q 30.
What is the maximum number of electrons that can go into the N shell of an atom ?
Q 31.
What name is given to those isotopes which have unstable nuclei and emit various types of radiations ?
Q 32.
State one use of radioactive isotopes in industry.
Q 33.
What are canal rays?
Q 34.
Fill in the blanks :
Rutherford's scattering experiment is related to to the size of ____________.
Q 35.
What is the maximum number of electrons which can be accommodated in the K shell of an atom
Q 36.
Which shell of an atom can accommodate a maximum of
(a) 8 electrons?
Q 37.
State the location of electrons, protons and neutrons in an atom.
Q 38.
What were the important features of atomic model based on Rutherford's scattering experiment?
Q 39.
What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons ?
Q 40.
Fill in the blanks :
________ rays are negatively charged.
Q 41.
Fill in the blanks :
The fundamental particle not present in hydrogen atom is __________.
Q 42.
Name the particles which actually determine the mass of an atom.
Q 43.
What is the absolute mass and charge of an electron ?
Q 44.
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 | Symbol |
|---|
| 11 | 12 | ........ | ....... | ........ | ......... |
Q 45.
Give one example of a radioactive isotope which is used as a fuel in the reactors of nuclear power plants.
Q 46.
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 47.
What valencies will be shown by the elements A, B, C, D and E having atomic numbers 2, 4, 8, 10, and 13 respectively.
Q 48.
Given that the percentage abundance of the isotope
Ne, is 90% and that of the isotope
Ne, is 10%,calculate the average atomic mass of neon.
Q 49.
(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 50.
(a) What are radioactive isotopes ? Give two examples of radioactive isotopes.
(b)Give any two uses of radioactive isotopes.
(c)An element Z contains two naturally occurring isotopes
Z and
Z. If the average atomic mass of this element be 35.5 u, calculate the percentage of two isotopes.
