How long would it take to count all the stars in the Milky Way Galaxy at a rate of one star per second?
A) several days
B) several weeks
C) several years
D) several thousand years
E) hundreds of thousands of years
D
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How do we know that pulsars must be neutron stars?
A) Pulsars have the same upper mass limit as neutron stars do. B) No massive object, other than a neutron star, could spin as fast as we observe pulsars to spin and remain intact. C) This is only a theory that has not yet been confirmed by observations. D) We have observed massive-star supernovae produce pulsars. E) Telescopic images of pulsars and neutron stars look exactly the same.
A sealed container holds 0.020 moles of ideal nitrogen (N2 ) gas, at a pressure of 1.5 atm and a temperature of 290 K. The atomic mass of nitrogen is 14.0 g/mol
How many molecules of nitrogen are in the container? (R = 8.31 J/mol ? K, 1 atm = 101 kPa) A) 1.5 × 1021 mol B) 3.0 × 1021 mol C) 6.0 × 1021 mol D) 1.2 × 1022 mol E) 2.4 × 1022 mol
The melting point of aluminum is 660°C, the latent heat of fusion is 4.0 × 105 J/kg and its specific heat is 900 J/(kg?K). How much heat must be added to 500 g of aluminum at 27°C to completely melt it?
A) 485 kJ B) 395 kJ C) 273 kJ D) 147 kJ E) 14 kJ
The jet streams
A) are high-speed winds in the upper troposphere. B) play an essential role in the transfer of heat energy from the Equator to the Poles. C) are generated by strong temperature and pressure gradients. D) are high speed winds generated by temperature and pressure differences.