A) 4.7 cm
The formula for the angular spread of the nth-maximum from the central bright fringe for a diffraction from two slits is

where
n is the order of the maximum
is the wavelength
is the distance between the slits
In this problem,
n = 5


So we find

And given the distance of the screen from the slits,

The distance of the 5th bright fringe from the central bright fringe will be given by

B) 8.1 cm
The formula to find the nth-minimum (dark fringe) in a diffraction pattern from double slit is a bit differente from the previous one:

To find the angle corresponding to the 8th dark fringe, we substitute n=8:

And the distance of the 8th dark fringe from the central bright fringe will be given by

The most massivest stars end their lives as black holes. <em>(D)</em>
Wings to fly. Without flying, birds would be near defenseless.
✿━━━━@♥ℳg━━━━✿
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Torque = Force X Displacement
= MLT-2 X L = [M1L2T-2]
The dimensional formula of force is MLT^-2
Batteries always use direct current. That eliminates A and C. The other part of the answers is just asking what direct/alternating means. Alternating currents change directions moving one way then another. Direct current only moves in one direction. Therefore, the answer is D, since the current is direct and direct currents move in one direction.