Answer: C) The net force on the brick is 0 N, and the brick remains at rest.
Answer: Option D is correct.
Explanation: Equation given by de Broglie is:

where,
= wavelength of the particle
h = Planck's constant
m = mass of the particle
v = velocity of the particle
In option A, football will have some mass and is moving with a velocity of 25 m/s, hence it will have some wavelength.
In Option B, unladen swallow also have some mass and is moving with a velocity of 38 km/hr, hence it will also have some wavelength.
In Option C, a person has some mass and is running with a velocity of 7 m/hr, hence it will also have some wavelength.
As, the momentum of these particles are large, therefore the wavelength will be of small magnitude and hence, is not observable.
From the above, it is clearly visible that all the options are having some wavelength, so option D is correct.
It blocks light waves from passing through.
Answer because it is made of many components that can be separated through physical means.
It cannot be a homogeneous mixture, as its composition is not uniform all throughout.
Answer:
Moles of zinc chloride produced are 0.09942 moles.
Explanation:

Mass of zinc used = 6.5 g
Moles of zinc =
According to reaction, 1 mol of zinc gives 1 mole of zinc chloride,then 0.09942 moles of zinc will give :
of zinc chloride
Moles of zinc chloride produced are 0.09942 moles.