Bohr's atomic model

when a copper compound is heated strongly in Bunsen Flame, it emits a greenish-blue flame because

• the copper atoms form copper ions

• the copper metal forms copper vapour

• energy is emitted by the electrons in the copper atoms

• energy is absorbed by the electrons in the copper atoms

the spectrum of hydrogen gas consists of several series of discrete lines because

• an electron in an permitted orbit will radiate energy

• electron move from higher energy levels to lover energy levels

• the electrons have enough energy to escape from the hydrogen atoms to form ions

• the electrons in hydrogen atoms move from the ground state to the excited state

the following figure shows the spectral lines in the Balmer series of the hydrogen spectrum. the line L is caused by the transition of electrons from

• n = 2 to n = 1

• n = 3 to n = 2

• n = infinity to n = 1

• n = infinity to n = 2

the lines in the Lyman series are shown below . Do the values of the wavelength and the frequency for the lines H1, H2, and H3 in the series increase or decrease?

• wavelength = decrease / frequency = increase

• wavelength = increase / frequency = decrease

• wavelength = decrease / frequency = decrease

• wavelength = increase / frequency = increase

which of the following statements is true of the Balmer series?

• the first line has the lowest frequency

• the lines in the series become closer when the frequency decreases

• the series is in the ultraviolet region

• the ionisation energy of hydrogen can be calculated from one of the spectral lines in the Balmer series

when an electric discharge is passed through helium gas at a low pressure,

• the helium atoms absorb energy

• electromagnetic radiation of certain wavelength is emitted

• a continuous spectrum is produced

the hydrogen spectrum is produced when

• electrons fall from the excited state to the ground state

• hydrogen atoms combine to form hydrogen molecules

• electrons are promoted to energy levels which are further from the atomic nucleus

in the Lyman series,

• the frequency of the convergence limit can be used to calculate the ionisation energy of hydrogen

• every line in the spectrum appears in the visible spectrum

• the line with the shortest wavelength is caused by the transition of electrons from n = 2 to n = 1

what is the maximum number of emission lines for a hydrogen atom with energy levels n = 1, n = 2, n = 3 and n = 4?

• 3

• 5

• 6

• 8

which of the following statements explains the emission spectrum of hydrogen atoms consists of discrete lines?

• the electron of hydrogen absorbs a photon of light and being promoted to a higher energy level

• electron transitions between energy levels emit or absorb certain amount of energy

• under ordinary conditions, the electron of hydrogen atoms is in the ground state

• the emission spectrum consists of discrete lines with certain frequencies