of zinc atom is . Å. Calculate (a) radius of zinc atom in pm and (b) number of atoms present in a length of . cm if the zinc atoms are arranged side by side lengthwise.
. A certain particle carries . × – C of static electric charge. Calculate the number of electrons present in it.
. In Milikan’s experiment, static electric charge on the oil drops has been obtained by shining X-rays. If the static electric charge on the oil drop is – . × – C, calculate the number of electrons present on it.
. In Rutherford’s experiment, generally the thin foil of heavy atoms, like gold, platinum etc. have been used to be bombarded by the α -particles. If the thin foil of light atoms like aluminium etc.
is used, what difference would be observed from the above results ? . Symbols Br and Br can be written, whereas symbols Br and Br are not acceptable. Answer briefly.
. An element with mass number contains . % more neutrons as compared to protons. Assign the atomic symbol.
. An ion with mass number possesses one unit of negative charge. If the ion conatins . % more neutrons than the electrons, find the symbol of the ion.
. An ion with mass number contains units of positive charge and . % more neutrons than electrons. Assign the symbol to this ion.
. Arrange the following type of radiations in increasing order of frequency: (a) radiation from microwave oven (b) amber light from traffic signal (c) radiation from FM radio (d) cosmic rays from outer space and (e) X-rays. . Nitrogen laser produces a radiation at a wavelength of .
nm. If the number of photons emitted is . × , calculate the power of this laser. .
Neon gas is generally used in the sign boards. If it emits strongly at nm, calculate (a) the frequency of emission, (b) distance traveled by this radiation in s (c) energy of quantum and (d) number of quanta