The number of electrons, neutrons and protons in a species are equal to 10, 8 and 8 respectively. The proper symbol of the species
A 600 W mercury lamp emits monochromatic radiation of wavelength 331.3 nm. How many photons are emitted from the lamp per second? (h = 6.626 x 10-34 Js; velocity of light = 3×108 ms-1).
1 × 1019
1 × 1022
1 × 1021
1 × 1023
The shortest wavelength in hydrogen spectrum of Lyman series when RH = 109678 cm-1 is
1002.7 Å
1215.67 Å
1127.30 Å
911.7 Å
The electrons, identified by quantum numbers n and l,
(I) n = 3; l = 2; (II) n = 5; l = 0; (III) n = 4; l = 1; (IV) n = 4; l = 2; (V) n = 4; l = 0;
can be placed in order of increasing energy as-
I < V < III < IV < II
I < V < III < II < IV
V < I < III < II < IV
V < I < II < III < IV
The number of photons emitted per second by a 60 W source of monochromatic light of wavelength 663 nm is (h = 6 .63 × 10-34 Js)
4 × 10-20
1.5 × 1020
3 × 10-20
2 × 1020
Energy released, when one atom of uranium undergoes nuclear fission according to the following reaction is (atomic mass of U = 235.060; n = 1.009; Ba= 143.881 and Kr = 89.94 7) about
92U235 + 0n1 → 56Ba144 + 36Kr90 + 2 0n1
235 MeV
208 MeV
931.5 MeV
5.33 x 1023 MeV
Identify the nuclear reaction that differs from the rest.
γ- decay
κ- capture
Positron emission
β-decay
A.
γ- decay
Positron emission, κ-capture, β-decay and α-decay, all of these processes cause change in either atomic number or in mass number or in both but γ-decay do not cause any change either in mass number or in atomic number, so it is different from the rest.
The radius of the first Bohr orbit of hydrogen atom is 0.529 Å. The radius of the third orbit of H+ will be
8.46 Å
0.705 Å
1.59 Å
4.29 Å
Which diagram best represents the appearance of the line spectrum of atomic hydrogen in the visible region?
The correct set of quantum numbers (n, l and m respectively) for the unpaired electron of chlorine atom is :
2, 1, 0
2, 1, 1
3, 1, 1
3, 2, 1