An element emits light at two nearly equal wavelengths, 577 nm and 579 nm if the light is normally incident on a diffraction grating with 2000 lines/cm., what is the distance between the 3rd order fringes of the two wavelengths on a screen 1 m from the grating?

1.2 mm

Explanation:

Distance of 3 rd order fringe from centre

=3\frac{\lambda D}{d}

where λ is wave length of light D is distance of screen and d is separation between two lines

So distance between 3 rd order fringe of two wavelengths

3\frac{D}{d}\left ( \lambda _1-\lambda _2 \right )\\

=\frac{3\times 1\times 2000}{1\times 10^{-2}}\left ( 579-577 \right )\times 10^{-9}m\\

=12\times 10^{-1}mm

  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

the answer would be   dignified - apex