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Showing 1476 to 1500 of 3046 questions (page 60 of 122).

1476. According to the special theory of relativity, the speed of light in free space is

A. dependent on the observer velocity B. infinite C. different for different observers D. the same for all inertial observers E. dependent on the source velocity

1477. In the photoelectric effect, the maximum kinetic energy of the emitted electrons is

A. hf B. independent of frequency C. hf - work function D. hf + work function E. work function - hf

1478. The de Broglie wavelength of a particle of momentum p is

A. h/p B. h/p2 C. hp D. p/h E. h p2

1479. The Compton effect demonstrates the

A. wave nature of light B. polarization of X-rays C. interference of X-rays D. particle nature of light E. transverse nature of light

1480. Heisenberg's uncertainty principle states that the product of the uncertainties in position and momentum is

A. equal to hf B. at least of the order of h/(4 pi) C. zero D. independent of h E. at most h

1481. The stopping potential in a photoelectric experiment depends on

A. the polarization of light B. the distance of the source C. the intensity of light only D. the frequency of light and the material E. the area of the cathode

1482. According to Bohr's theory, the angular momentum of an electron in the nth orbit is

A. n2 h B. nh/(2 pi) C. h/(2 pi n) D. h/n E. nh

1483. The spectral series of hydrogen that lies in the visible region is the

A. Lyman series B. Pfund series C. Balmer series D. Brackett series E. Paschen series

1484. The ionization energy of a hydrogen atom in its ground state is

A. 10.2 eV B. 27.2 eV C. 1.51 eV D. 3.4 eV E. 13.6 eV

1485. Laser action requires

A. population inversion B. thermal equilibrium C. a very low pumping rate D. a single energy level E. incoherent sources

1486. The continuous part of an X-ray spectrum is produced by

A. electron transitions between inner shells B. deceleration of fast electrons in the target C. thermal emission from the filament D. nuclear decay E. stimulated emission

1487. The radius of the nth Bohr orbit in hydrogen is proportional to

A. n2 B. n3 C. 1/n D. n E. 1/n2

1488. Isotopes of an element have the same

A. atomic mass B. mass number C. binding energy D. atomic number E. number of neutrons

1489. A radioactive sample has a half life of 10 days. The fraction remaining after 30 days is

A. 1/4 B. 1/3 C. 1/2 D. 1/16 E. 1/8

1490. In beta minus decay, the atomic number of the nucleus

A. decreases by 2 B. decreases by 1 C. increases by 1 D. increases by 2 E. remains unchanged

1491. The energy released in nuclear reactions arises from

A. frictional heating B. electron transitions C. chemical bonding D. mass defect E. ionization

1492. Energy production in the Sun is mainly due to

A. radioactive decay of uranium B. gravitational contraction alone C. nuclear fusion D. nuclear fission E. chemical combustion

1493. Which radiation has the greatest penetrating power?

A. beta B. gamma C. alpha D. proton E. neutron in air only

1494. In a nuclear reactor, the moderator is used to

A. slow down fast neutrons B. shield the operators C. increase the fuel temperature D. control the coolant flow E. absorb excess neutrons

1495. The value of Avogadro's number is

A. 6.02 x 10^24 B. 3.01 x 10^23 C. 6.02 x 10^23 D. 6.02 x 10^22 E. 1.66 x 10^-24

1496. The molar volume of an ideal gas at standard temperature and pressure is

A. 11.2 dm3 B. 44.8 dm3 C. 24 dm3 D. 22.414 dm3 E. 1 dm3

1497. The reactant that is completely consumed first and therefore limits the amount of product is called the

A. intermediate B. limiting reactant C. catalyst D. spectator species E. excess reactant

1498. A compound contains 40% carbon, 6.7% hydrogen and 53.3% oxygen by mass. Its empirical formula is

A. CH2O B. C2H4O2 C. C2H6O D. CH4O E. CHO

1499. The number of moles in 9.8 g of sulphuric acid is

A. 0.2 B. 0.1 C. 1.0 D. 0.98 E. 0.05

1500. The number of molecules in 11.2 dm3 of oxygen gas at STP is

A. 1.5 x 10^23 B. 1.204 x 10^24 C. 6.02 x 10^23 D. 3.01 x 10^23 E. 6.02 x 10^22

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