As a monochromatic light ray passes from air
into water, two characteristics of the ray that will
not change are
(1) wavelength and period
(2) frequency and period
(3) wavelength and speed
(4) frequency and speed

The correct answer is

(2) frequency and period

In fact, when a light wave moves from one medium to another, its speed and its wavelength change. On the contrary, the frequency of the wave remains the same. Since the period is the reciprocal of the frequency:

this means that the period of the wave does not change neither. So, the correct answer is

(2) frequency and period

the second one and the forth one are in the purple because they are opinions and the rest are in the yellow

explanation:

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz