- D To balance the superscripts, we write 2 + 2 = 3 + A, and get A = 1. Now, to
balance the subscripts, we write 1 + 1 = 2 + Z, so Z = 0. Therefore, the
particle X has a mass number of 1 and a charge of 0; it’s a neutron. - B We use the equation q=mcΔT to find ΔT.
- D From the kinetic theory of gases, we know that the average kinetic energy
of the molecules of an ideal gas is directly proportional to the absolute
temperature. This eliminates (B) and (C). Furthermore, the fact that KEavg ∝
T implies that the root-mean-square speed of the gas molecules, vrms, is
proportional to the square root of the absolute temperature. This eliminates
(A) and (E). - A Ice melts at 0°C and boils at 100°C. During these phase transitions, the
temperature remains constant. Therefore, the graph of the sample’s
temperature must be momentarily flat at both 0°C and at 100°C. - C Relative to the central maximum, the locations of the bright fringes on the
screen are given by the expression mL(λ/d), where λ is the wavelength of the
light used, L is the distance to the screen, d is the separation of the slits, and
m is an integer. The width of a fringe is, therefore (m + 1)L(λ/d) − mL(λ/d) =
λL/d. One way to increase λL/d is to decrease d. - E If the photons of the incident light have insufficient energy to liberate
electrons from the metal’s surface, then simply increasing the number of these
weak photons (that is, increasing the intensity of the light) will do nothing. To
produce photoelectrons, each photon of the incident light must have an energy
at least as great as the work function of the metal.
marvins-underground-k-12
(Marvins-Underground-K-12)
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