During refraction, waves bend when they pass from one medium to another. the waves refract because their changes. a) appearance b) intensity c) size d) speed

Speed

Explanation:

When waves travel in different mediums then due to change in the speed of the wave the path of the wave will change.

Initially wave is travelling in the given direction with some speed "v"

now when the medium of the wave will change then it will change the speed as we know that

now due to this change in the refractive index of the speed and hence the wavelength will change in different mediums

So here correct answer will be

D) Speed

  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