Answer: ok
Explanation:
The molecules in hot air are moving faster than the molecules in cold air. Because of this, the molecules in hot air tend to be further apart on average, giving hot air a lower density. That means, for the same volume of air, hot air has fewer molecules and so it weighs less.
Answer:
The kinetic energy of the ejected electrons increases.
Explanation:
As we know that electrons are only ejected from a metal surface if the frequency of the incident light increases the work function of the metal. If the frequency of the incident light is less than the work function of the metal no matter how intense the beam the electrons will not be ejected from the surface.
Using conservation of energy principle we have
If we increase the intensity of incident light the term on the LHS of the above equation increases this increase appears in the kinetic energy term in RHS of the equation since 
remains constant.
Answer: B or "diamonds are rare,valuable gems".
Explanation:
since the link does not show very much, I don't know if A is correct or not. D is incorrect because that is an opinion. C is incorrect.
The wavelength decreases to roughly half.
(The frequency roughly doubles.)
Answer:
No we cannot
Explanation:
But what causes a ring to appear around the moon? This phenomenon is called a "moon halo." According to the National Weather Service, this ring of light, which is actually an optical illusion, forms around the moon when moonlight refracts off ice crystals in cirrus clouds, high up in the Earth's atmosphere.
