If sunlight shines straight onto a peacock feather, the feather appears bright blue when viewed from 15° on either side of the incident beam of light. the blue color is due to diffraction from parallel rods of melanin in the feather. other wavelengths in the incident light are diffracted at different angles, leaving only the blue light to be seen. the average wavelength of blue light is 470 nm. assuming this to be the first order diffraction, what is the spacing of the melanin rods in the feather?

  d = 1.82 10⁻⁶ m = 1.82 μm

Explanation:

The diffraction phenomenon is explained by a similar equation Young's double slit equation

    d sin θ = n λ

Where d is the spacing between the bars, θ is the angled diffraction, n in an integer representing the order of diffraction and λ is the wavelength of light

Let's calculate

     d = n λ / sin θ

     d = 1 470 10⁻⁹ /sin 15

     d = 1.82 10⁻⁶ m = 1.82 μm

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂