Measuring density is very important for many different industries because the density measurement will help determine the characteristics of a material, for example, whether the material will float or sink. Knowing the density of a material helps in determining the mass and volume of a material, all of which are extremely important measurements in all industries.
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Related questions (More answers below)
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.
Is constant (matter that has a composition that is the same everywhere)
Answer:
This is known as the coefficient factor
Explanation:The balanced equation makes it possible to convert information about one reactant or product to quantitative data about another element.
Answer:HNO3 + NaOH → H2O + NaNO3
Explanation: