Question:
Write a short note on Nucleus.
Answer:
- Nucleus of an atom consists of fundamental particles, protons and neutrons, collectively called as nucleons.
- Nucleus is positively charged due to the presence of protons.
- Nucleus is highly dense and largely reponsible for the mass of the atom.
- Size of the nucleus as compared to atomic size is very less (1000th of atomic radius).
Structure of the Atom
Q 1.
Who discovered electrons?
Q 2.
If A = 23 and Z = 11 for Na atom, how many protons, electrons and neutrons present in Na atom?
Q 3.
What were the important features of atomic model based on Rutherford's scattering experiment?
Q 4.
Who discovered protons?
Q 5.
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 6.
Fill in the blanks :
Rutherford's scattering experiment is related to to the size of ____________.
Q 7.
How many times is a proton heavier than an electron ?
Q 8.
Write a short note on Nucleus.
Q 9.
If an atom contains one electron and one proton, will it carry any charge or not?
Q 10.
Describe briefly Thomson's model of an atom.
Q 11.
Fill in the blanks :
In the three fundamental sub-atomic particles, _________ are negatively charged, _________ are positively charged and ____________ have no charges.
Q 12.
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 13.
What is the maximum number of electrons which can be accommodated in the L shell of an atom
Q 14.
State one use of radioactive isotopes in medicine.
Q 15.
What is the maximum number of electrons an M shell of the atom can accommodate ?
Q 16.
Name the scientist who discovered electron.
Q 17.
Fill in the blanks :
________ rays are negatively charged.
Q 18.
Fill in the blanks :
Anode rays are also called ___________.
Q 19.
What is a proton ? How does it differ from a neutron ?
Q 20.
What is the electronic configuration of a hydrogen atom
Q 21.
State the number of electrons present in the outermost shell of the atoms of the following elements :
(i) Neon(ii)Chlorine
Q 22.
What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons ?
Q 23.
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 24.
Complete the following statements :
(a) Magnesium has 2 valence electrons in the......... shell.
(b)The valency of nitrogen in N2 molecule is........
(c)Isotopes have different mass numbers because their nuclei contain different number of........
(d) Some boron atoms have mass number 10 and some have mass number 11. These boron atoms with different mass numbers are called............
Q 25.
Give one use each of the following radioactive isotopes :
(a)Uranium-235 (b) Cobalt-60
Q 26.
(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 27.
What were the observations of Rutherford's ?-scattering experiment?
Q 28.
What is mass number?
Q 29.
Fill in the blanks :
_______ are atoms having the same mass number but different atomic numbers.
Q 30.
How does a proton differ from an electron ?
Q 31.
Compare an electron, a proton and a neutron in respect of their relative masses and charges.
Q 32.
Fill in the following blanks
Atomic
number | Mass number | Protons | Neutrons | Electrons | Symbol |
|---|
| 10 | 22 | ....... | ........ | ....... | ........ |
Q 33.
(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.
Q 34.
Fill in the blanks :
The maximum number of electrons that can be accommodated in L-shell are _______.
Q 35.
Name the shell of an atom which can accommodate a maximum of
(a) 2 electrons (b) 18 electrons
Q 36.
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 37.
What are canal rays?
Q 38.
What are cathode rays?
Q 39.
On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?
Q 40.
What are the limitations of Rutherford’s model of the atom?
Q 41.
What is ionization energy?
Q 42.
What is the absolute mass and charge of an electron ?
Q 43.
Name the radioactive isotope which is used in the treatment of cancer.
Q 44.
Which radioactive isotope is used to determine the activity of thyroid gland ?
Q 45.
State one use of radioactive isotopes in industry.
Q 46.
State whether the following statement is true or false :
Radioactive isotope of iodine is used for making the medicine called tincture iodine.
Q 47.
What name is given to the pair of atoms such as
N and
N ?
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.
Who is known as 'Father of Nucleus Physics'?
Q 50.
Fill in the blanks :
Atomic number is equal to _____________.
