E mass number of any given atom depends solely on the number of protons and neutrons in its nucleus. The mass number of any atom can be determined by adding the number of protons and neutrons. (Mathematically this is stated as Mass Number = Protons + Neutrons). For instance, a Carbon atom with 6 protons and 6 neutrons will have a mass number of 12AMU. However, a Carbon atom with 6 protons and 8 Neutrons will have a mass number of 14AMU. They are both Carbon atoms, however they each have a different mass number. Atoms of the same element that have different numbers of neutrons, and therefore, different mass numbers, are called isotopes. Isotopic symbols are used to indicate isotopes of the same elements. In the following isotopic symbols the lower number is the atomic number…it is the number of protons. The upper number is the mass number, it represents to sum of the protons and neutrons in the atoms nucleus.
During the phase transition vapour --> liquid water, the temperature of the water does not change; the molecules of water release heat and the amounf of heat released is equal to
where
m is the mass of the water
is the latent heat of evaporation.
For water, the latent heat of evaporation is
, while the mass of the water is
so, the amount of heat released in the process is
Answer:
C. Atoms
Explanation:
The basic unit of matter and the smallest, indivisible unit of a chemical element. It comprises a nucleus (neutrons + protons) that is surrounded by a cloud of electrons.
You can tell a lot about an object that's not moving,
and also a lot about the forces acting on it:
==> If the box is at rest on the table, then it is not accelerating.
==> Since it is not accelerating, I can say that the forces on it are balanced.
==> That means that the sum of all forces acting on the box is zero,
and the effect of all the forces acting on it is the same as if there were
no forces acting on it at all.
==> This in turn means that all of the horizontal forces are balanced,
AND all of the vertical forces are balanced.
Horizontal forces:
sliding friction, somebody pushing the box
All of the forces on this list must add up to zero. So ...
(sliding friction force) = (pushing force), in the opposite direction.
If nobody pushing the box, then sliding friction force = zero.
Vertical forces:
gravitational force (weight of the box, pulling it down)
normal force (table pushing the box up)
All of the forces on this list must add up to zero, so ...
(Gravitational force down) + (normal force up) = zero
(Gravitational force down) = -(normal force up) .
