Page 1 - 4.HOME ASSIGNMENT-(BOHR'S MODEL OF AN ATOM)
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SAI International School
                                                       Class-IX
                                                Subject-Chemistry
                                             Topic-Structure of atom
                                     Sub topic- Bohr’s model of an atom
                OBJECTIVE QUESTIONS
                 Q.1     Assertion: Bohr’s orbits are called stationary orbits.
                         Reason: Electrons remain stationary in these orbits for some time.
                 Q.2     Assertion: Electrons moving in the same orbit will lose or gain energy.
                         Reason: On jumping from higher to lower energy level, the electron will
                         gain energy.
                 Q.3     Assertion:  Electrons radiate energy when they jump from one orbit to
                         another.
                         Reason: Electrons are allowed in discrete orbits.
                 Q.4     Assertion: Neutrons are neutral particles.
                         Reason: Neutrons present inside the nucleus of an atom.
                 Q.5     Assertion: Orbits are also called energy levels.

                         Reason: Orbits are associated with some energy.
                 Q.6      In Bohr’s model how do electrons travel?
                             a)  Electrons move in and out of the nucleus.
                             b)  Electrons do not move
                             c)  Electrons move in circular paths called orbits around the nucleus.
                             d)  Electrons move in the straight line.
                 Q.7     Which of the following statements are part of Bohr’s model of hydrogen atom?
                            a)  Energy of the electrons in the orbit is quantized.
                            b)  The electron in the orbit nearest to the nucleus has the lowest energy.
                            c)  Electrons revolve in different orbits around the nucleus.
                            d)  All of these


               SUBJECTIVE
            Sl.No.     Questions                                                                   Mark
            Q.1        Name the particles which determine the mass of an atom.                     1

            Q.2        Electrons can change their orbits by absorbing or emitting energy.          1
                       (True/False)
            Q.3        Write  two  points  of  difference  between  protons,  electrons  and       3
                       neutrons.
            Q.4        Write the postulates of Bohr’s model of an atom?                            3
            Q.5        State the major drawback in Rutherford’s model of an atom. Mention two      5
                       features of Bohr’s model which helped compensate this drawback.










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