Our current Gregorian calendar usually has a leap year every 4 years, but there are exceptions in some century years (e.g., 2100 will not be a leap year). Which of the following best explains why the calendar needs these exceptions?
A) The length of the tropical year (from one March equinox to the next) is not exactly 365-1/4 days.
B) Precession of Earth's axis makes the tropical year (from one March equinox to the next) slightly different from the sidereal year (Earth's actual orbital period).
C) Earth's orbital period around the Sun is gradually changing due to tidal forces.
D) The exceptions are necessary to account for the difference between a solar and sidereal day.
A) The length of the tropical year (from one March equinox to the next) is not exactly 365-1/4 days.
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Molar Specific Heats: For an ideal gas,
A. 
= 1 for all ideal gases.
B. 
< 1 for all monatomic and diatomic gases.
C. 
> 1 for all monatomic and diatomic gases.
D. 
< 1 only for a monatomic gas.
E. 
< 1 only for a diatomic gas.
Arcturus shows a large proper motion, almost perpendicular to the galactic plane. What Population does it belong to, and why?
What will be an ideal response?
A heavy stone and a light stone are released from rest in such away that they both have the same amount of gravitational potential energy just as they are released. Air resistance is negligibly small
Which of the following statements about these stones are correct? (There could be more than one correct choice.) A) The initial height of the light stone is greater than the initial height of the heavy stone. B) The stones must have been released from the same height. C) The stones both have the same speed just as they reach the ground. D) Just as it reaches the ground, the light stone is traveling faster than the heavy stone. E) The stones both have the same kinetic energy just as they reach the ground.
Which of the following is a negatively charged polyatomic ion?
a. Ammonium ion b. Oxide ion c. Sodium ion d. Nitrate ion