Question

136. Which of the radiation with highest wave number 1) Microwaves 2) X - rays 3) I.R. - rays 4) Radiowaves 137. The metal best used in photoelectric cells is 1) Na 2) Mg 3) Al 4) Cs 138. Kinetic energy of photoelectrons is independent on...... of incident radiation 1) Wavelength 2) Wave number 3) Frequency 4) Intensity 139. If the wavelength of an electromagnetic radiation is 20000A. What is theenergy in ergs ? 1) 9.94 x 10-12 2) 9.94 x 10-10 3) 4.97 x 10-12 4) 4.97 x 10-19 140. The energy of an electromagnetic radiation is 19.875 x 10-13 ergs. What is the wave number in cm-1 ? (h = 6.625 x 10-27 erg. sec ; c = 3 x 1010 cm.sec-1) 1) 1000 2) 106 3) 100 4) 10,000 141. Energy equal to the mass of one electron is 1) 8.2 x 10-7 erg 2) 9.2 x 10-8 erg 3) 8.2 x 10-10 erg 4) 4.1 x 10-8 erg 142. According to Planck’s Quantum theory, the correct statements are a) The atoms and molecules in the black body does not emit radiationcontinuously b) Radiation is emitted in the form of smallest quantity of energy called Quantum c) Energy associated with emitted radiations is inversely proportional to frequency d) The emitted radiant energy is propagated in the form of waves 1) a, b, c 2) b, c 3) a, b, d 4) b, d, c 143. The ratio of energies of two photons of wavelengths 2000 and 4000 A0 1) 1 : 4 2) 4 : 1 3) 1 : 2 4) 2 : 1 144. The threshold frequency 0  for a metal is 7 x 1014 s - 1. The kinetic energy of electron emitted when radiation of frequency 1 x 1015 s-1 hits the metal is 1) 1.988 x 10-17 J 2) 1.988 x 10-19 J 3) 16.32 x 10-19 J 4) 13.7 x 10-17 J 145. The order of the work function of alkali metals is 1) Li > Na > K > Rb 2) Na > K > Rb > Li 3) Rb > K > Na > Li 4) Li > K > Na > Rb 146. Bohr’s theory is applicable to 1) Li+2 2) Li+ 3) He+ 4) Both 1 and 3 147. Bohr’s theory is not applicable to 1) H 2) He+ 3) Li2+ 4) H+ 148. The angular momentum of an electron present in the excited state of hydrogen is 1.5h/ .  The electron is present in 1) Third orbit 2) Second orbit 3) Fourth orbit 4) Fifth orbit 149. Radius of tenth Bohr orbit of the hydrogen atom is 1) 0.53 A0 2) 5.3 A0 3) 53A0 4) 5.3 x 5A0 150. The radius of which of the following orbit is same as that the first Bohr’s orbit of hydrogen atom ? 1) He+(n=2) 2) Li2+(n=2) 3) Li2+(n=3) 4) Be3+(n=2)

plz answer fast

Answer 1

Explanation:

136)2

137)4

138)4

139)1

140)

141)1

142)

143)4

144)2

soory for delay till how many minutes are there

Edited

146)4

147)4

148)1

149)1

150)4

Answer 2

Answer:

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