Explanation:
Given that,
Wavelength of light, 
Angle, 
We need to find the slit spacing for diffraction. For a diffraction, the first order principal maximum is given by :

n is 1 here
d is slit spacing

So, the slit spacing is
.
Answer:
remove contamination; pollution ; test ground water and dirt .
Codominence i think, its both parents genes are used
Answer:

Explanation:
Given that
Mass of rifle = M
Initial velocity ,u= 0
Mass of bullet = m
velocity of bullet = v
Lets take final speed of the rifle is V
There is no any external force ,that is why linear momentum of the system will be conserve.
Initial linear momentum = Final linear momentum
M x 0 + m x 0 = M x V + m v
0 = M x V + m v

Negative sign indicates that ,the recoil velocity will be opposite to the direction of bullet velocity.