Consider ‘postulate’ given below. Given any two distinct points A and B, there exists a third point C which is between A and B. Do this postulate contains any undefined term ? Is this postulate consistent ? Do they follow from Euclid’s postulate ? Explain.

Consider ‘postulate’ given below. There exist at least three points that are not on the same line. Do this postulate contains any undefined term ? Is this postulate consistent ? Do they follow from Euclid’s postulate ? Explain.

Consider the following statement : There exists a pair of straight lines that are everywhere equidistant from one another. Do you think that this statement is (or is not) a direct consequence of Euclid’s fifth postulate ? Explain.

The question given below consist of an assertion (A) and a reason ( R). Use the following key to choose the appropriate answer to these questions from the codes (a), (b), ( c) and (d) given below: Both A and R are true and R is the correct explanation of A. Both A and R are true but R is NOT the correct explanation of A. A is true but R is false. A is false and R is also false. Assertion: Insulators do not follow electric current to flow through them. Reason:Insulators have large number of free electrons.

Bohr's model of hydrogen atom In order to explain the stability of atom and its line spectra, Bohr gave a set of postulates: An electron in an atom revolves in certain circular orbit around the nucleus. These are the orbits for which mvr=(nh)/(2pi) In these allowed orbits, the electron does not radiate energy. When an electron jumps from higher energy level E_(n_2) to lower energy orbit E_(n_1) , radiation is emittd and frequency of emitted electron is given by v=(E_(n_2)-E_(n_1))/h . Further the radius of the n^(th) orbit of hydrogen atom is r=(n^2h^24piepsilon_0)/(4pi^2me^2) and energy of the n^(th) orbit is given by E_n=-13.6/n^2 eV . If 13.6 eV energy is required to ionise the hydrogen atom, then enegy required to remove an electron from n=2 is:

Bohr's model of hydrogen atom In order to explain the stability of atom and its line spectra, Bohr gave a set of postulates: An electron in an atom revolves in certain circular orbit around the nucleus. These are the orbits for which mvr=(nh)/(2pi) In these allowed orbits, the electron does not radiate energy. When an electron jumps from higher energy level E_(n_2) to lower energy orbit E_(n_1) , radiation is emittd and frequency of emitted electron is given by v=(E_(n_2)-E_(n_1))/h . Further the radius of the n^(th) orbit of hydrogen atom is r=(n^2h^24piepsilon_0)/(4pi^2me^2) and energy of the n^(th) orbit is given by E_n=-13.6/n^2 eV . The angular momentum of the orbital electron is integarl multiple of

Bohr's model of hydrogen atom In order to explain the stability of atom and its line spectra, Bohr gave a set of postulates: An electron in an atom revolves in certain circular orbit around the nucleus. These are the orbits for which mvr=(nh)/(2pi) In these allowed orbits, the electron does not radiate energy. When an electron jumps from higher energy level E_(n_2) to lower energy orbit E_(n_1) , radiation is emittd and frequency of emitted electron is given by v=(E_(n_2)-E_(n_1))/h . Further the radius of the n^(th) orbit of hydrogen atom is r=(n^2h^24piepsilon_0)/(4pi^2me^2) and energy of the n^(th) orbit is given by E_n=-13.6/n^2 eV . When hydrogen atom is the first excited level, it radius is:,

Bohr's model of hydrogen atom In order to explain the stability of atom and its line spectra, Bohr gave a set of postulates: An electron in an atom revolves in certain circular orbit around the nucleus. These are the orbits for which mvr=(nh)/(2pi) In these allowed orbits, the electron does not radiate energy. When an electron jumps from higher energy level E_(n_2) to lower energy orbit E_(n_1) , radiation is emittd and frequency of emitted electron is given by v=(E_(n_2)-E_(n_1))/h . Further the radius of the n^(th) orbit of hydrogen atom is r=(n^2h^24piepsilon_0)/(4pi^2me^2) and energy of the n^(th) orbit is given by E_n=-13.6/n^2 eV . What would happen, if the electron in an atom is stationary?

Bohr's model of hydrogen atom In order to explain the stability of atom and its line spectra, Bohr gave a set of postulates: An electron in an atom revolves in certain circular orbit around the nucleus. These are the orbits for which mvr=(nh)/(2pi) In these allowed orbits, the electron does not radiate energy. When an electron jumps from higher energy level E_(n_2) to lower energy orbit E_(n_1) , radiation is emittd and frequency of emitted electron is given by v=(E_(n_2)-E_(n_1))/h . Further the radius of the n^(th) orbit of hydrogen atom is r=(n^2h^24piepsilon_0)/(4pi^2me^2) and energy of the n^(th) orbit is given by E_n=-13.6/n^2 eV . The ground state energy of hydroen atom is -13.6 eV. The KE and PE of the electron in this state are

The questions given below consist of an assertion and the reason. Use the following key to choose the appropriate answer. (a) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion. (b) The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.(c) Assertion is is CORRECT but reason is INCORRECT. (d) If assertion is INCORRECT but reason is CORRECT. (e)If both assertion and reason are INCORRECT. Assertion: In any time ionic solid with Schottky defects, the number of positive and negative ions are same. Reason: Equal number of cation and anion vacancies are present.

Observe the histogram (fig.) and answer the question given below: (i) What information is being given by the histogram? (ii) Which group contains maximum girls. (iii) How many girls have height 145 cms. and more? (iv) If we divide the girls into the following three categories, how many would there be in each? 150 cm and more - Group A 140 cm to less than 150 cm - Group B Less than 140 cm - Group C