Answer:
The grating spacing of the beetle is 
Explanation:
The concept to solve this problem is relate to interference effect given in the Young's Slits. Here was demonstrated that the length of the side labelled \lambda is known as the path difference. The equation is given by,

Where,
= wavelenght of light
N = a positive integer: 1,2,3...
= Angle from the center of the wall to the dark spot
d= width of the slit
Replacing our values we have that for n=1,



Therefore the grating spacing of the beetle is 
The best method to separates mixture of salt and water is evaporation. Take a small sample of mixture in a china dish. Heat it till all water evaporate. The residual remain is salt. Josh should use this method to separate salt from water.
Answer:
B and C
Explanation:
Because EMWs are varying magnetic and electric radiation traveling at 90° to each other propagating energy form one place to another through vibration of these magnetic and electric fields
Answer:
Should be B
Explanation:
As the light enters the prism at an angle, the glass causes the light to travel slower. The speed is affected by the frequency of the light. So each frequency is slowed by a different amount, causing the colors to separate.
Hope this helps!