Ask questions which are clear, concise and easy to understand.
Ask QuestionPosted by Anandhi Lajju 6 years, 5 months ago
- 0 answers
Posted by Deepak Chetry 6 years, 5 months ago
- 1 answers
Sia ? 6 years, 5 months ago
Check NCERT Solutions here : https://mycbseguide.com/ncert-solutions.html
Posted by Aryan K G 6 years, 5 months ago
- 1 answers
Manan Aggarwal?? 6 years, 5 months ago
Posted by Garima Sharma 6 years, 5 months ago
- 1 answers
Sia ? 6 years, 5 months ago
Molecular mass of CO2 = Atomic mass of C + 2 {tex}\times{/tex} Atomic mass of O
= (12u + 2 {tex}\times{/tex} 16u) = 44u
Gram molecular mass of CO2 = 44 g
1 gram molecule of CO2 = 44 g
0.72 gram molecule of CO2 {tex} = \frac{{\left( {44g} \right)}}{{\left( {1g} \right)}} \times \left( {0.72g} \right) = 31.68g{/tex}
Posted by Mohandas Gowda 6 years, 5 months ago
- 1 answers
Sia ? 6 years, 5 months ago
Atomic radius is defined as the distance from the centre of the nucleus of atom to the outermost shell of electrons.
Posted by Ayush Kumar 6 years, 5 months ago
- 0 answers
Posted by Charu Sharma 6 years, 5 months ago
- 1 answers
Posted by Charu Sharma 6 years, 5 months ago
- 3 answers
#Ãbhîst Sîñgh 6 years, 5 months ago
Renu Yadav 6 years, 5 months ago
Karan Sidhu 6 years, 5 months ago
Posted by Harshita Sharma 6 years, 5 months ago
- 1 answers
Sia ? 6 years, 5 months ago
Molality is temperature independent while molarity decreases with increase in concentration. This is because of expansion or contraction of the liquid with temperature.
Posted by Yamini Lariya 6 years, 5 months ago
- 2 answers
Manshi Panwar 6 years, 5 months ago
Posted by Karuna Kumari 6 years, 5 months ago
- 2 answers
Yogita Ingle 6 years, 5 months ago
Bohr model of the atom was proposed by Neil Bohr in 1915. It came into existence with the modification of Rutherford’s model of an atom. Rutherford’s model introduced the nuclear model of an atom, in which he explained that a nucleus (positively charged) is surrounded by negatively charged electrons. Bohr modified this atomic structure model by explaining that electrons move in fixed orbital’s (shells) and not anywhere in between and he also explained that each orbit (shell) has a fixed energy level. Rutherford basically explained nucleus of an atom and Bohr modified that model into electrons and their energy levels.
Postulates of Bohr’s Model of an Atom
- In an atom, electrons (negatively charged) revolve around the positively charged nucleus in a definite circular path called as orbits or shells.
- Each orbit or shell has a fixed energy and these circular orbits are known as orbital shells.
- The energy levels are represented by an integer (n=1, 2, 3…) known as the quantum number. This range of quantum number starts from nucleus side with n=1 having the lowest energy level. The orbits n=1, 2, 3, 4… are assigned as K, L, M, N…. shells and when an electron attains the lowest energy level it is said to be in the ground state.
- The electrons in an atom move from a lower energy level to a higher energy level by gaining the required energy and an electron moves from a higher energy level to lower energy level by losing energy.
Posted by Karuna Kumari 6 years, 5 months ago
- 0 answers
Posted by Kumar Anish 6 years, 5 months ago
- 0 answers
Posted by Sahil Varma 6 years, 5 months ago
- 1 answers
Posted by Parth Vasava 6 years, 5 months ago
- 0 answers
Posted by Aneena Mani 6 years, 5 months ago
- 1 answers
Posted by Harsh Sinha 6 years, 5 months ago
- 1 answers
#Ãbhîst Sîñgh 6 years, 5 months ago
Posted by Rishika Srivastav 6 years, 5 months ago
- 0 answers
Posted by Taniksha Nayal 6 years, 5 months ago
- 4 answers
Posted by Dev Kumar 6 years, 5 months ago
- 3 answers
Posted by Nitish Soni 6 years, 5 months ago
- 1 answers
Posted by Raj Singh 6 years, 5 months ago
- 3 answers
Posted by Sumit Chauhan 6 years, 5 months ago
- 3 answers
Aman Yadav 6 years, 5 months ago
Posted by Isha Sahu 6 years, 5 months ago
- 1 answers
Ayushi Chauhan 6 years, 5 months ago
Posted by Neelam Kumari 6 years, 5 months ago
- 1 answers
Yogita Ingle 6 years, 5 months ago
The Quantum Theory of Radiations by Max Planck can explain the photoelectric effect very well. Max Planck says that light is made of bundles of energy known as photons, energy of each photon being equal to hγ, γ being the frequency of the light. So when a photon of frequency being equal to the threshold frequency of the metal strikes the metal surface, it imparts its whole energy to an electron and hence helps the electron to overcome the forces of attraction from the nucleus of the atom. In this way an electron is ejected out of a metal surface when a photon strikes it. If the frequency of the photon is less that γ0 (threshold frequency), then no photoelectric effect is observed.
But if γ>γ0 , then some of its energy (which is equal to the ionization energy) is consumed in ejecting the electron from the metal and the remaining is used to impart some kinetic energy to the ejected electron.
Hγ= Ф + (½)mv2
Here, Ф is the ionization energy, v is the velocity imparted to the ejected electron, m is the mass of the electron.
As Ф=hγ0 , hγ= hγ0 + (½)mv2
Rearranging, (½)mv2 = h (γ-γ0)………….(1)
Equation (1) is called Einstein photoelectric equation.
Posted by Shyam Wagh 6 years, 5 months ago
- 1 answers
Yogita Ingle 6 years, 5 months ago
(i) Drawbacks of Rutherford’s atomic model— According to Rutherford’s model, electrons are orbiting the nucleus ; hence, the direction of their velocity is constantly changing, i.e., the electrons are accelerating. This will cause the electrons to emit or radiate energy; and consequently, the electrons will have lesser and lesser energy will get closer and closer to the nucleus, until at last it spirals into the nucleus.
(ii) An electron moving inward along a spiral path must continuously radiate energy. However in actual practice spectral lines of fixed wavelength are observed.
myCBSEguide
Trusted by 1 Crore+ Students
Test Generator
Create papers online. It's FREE.
CUET Mock Tests
75,000+ questions to practice only on myCBSEguide app
