Two factors determine whether a substance is a solid, a liquid, or a gas: The kinetic energies of the particles (atoms, molecules, or ions) that make up a substance. Kinetic energy tends to keep the particles moving apart. The attractive intermolecular forces between particles that tend to draw the particles together.
De broglie wavelength,
, where h is the Planck's constant, m is the mass and v is the velocity.

Mass of hydrogen atom, 
v = 440 m/s
Substituting
Wavelength 

So the de broglie wavelength (in picometers) of a hydrogen atom traveling at 440 m/s is 902 pm
Answer:
Explanation:
the object will not move as the force exerted is not sufficient enough to overcome its force of friction
Answer:
W has the lowest density and Y has the greatest density
Explanation:
Density of W = mass/volume = 11/24 = 0.45
Density of X = mass/volume = 11/12 = 0.91
Density of Y = m/v = 5.5/4 = 1.375
Density of Z = m/v = 5.5/11 = 0.5
From these we can find the answer......
Hope this answer is useful......
Answer:

Explanation:
M = Mass of each star
T = Time period = 15.5 days
v = Orbital velocity = 230 km/s
G = Gravitational constant = 
Radius of orbit is given by

We have the relation

The mass of each star is 