The number of electrons, neutrons and protons in a species are equal to 10, 8 and 8 respectively. The proper symbol of the species

• ${}_8{}^{16}\mathrm{O}$

• ${}_8{}^{16}\mathrm{O}^{2-}$

• ${}_8{}^{16}\mathrm{O}^{-}$

• ${}_8{}^{18}\mathrm{O}$

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 R_H = 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

348.

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