Atoms found in nature are either stable or unstable. An atom is stable if the forces among the particles that makeup the nucleus are balanced. An atom is unstable (radioactive) if these forces are unbalanced; if the nucleus has an excess of internal energy. Instability of an atom's nucleus may result from an excess of either neutrons or protons. Ccredits: internet source
The correct answer to the question is C).Dry ice changes to carbon dioxide when kept in an open container.
EXPLANATION:
Before answering this question, first we have to understand sublimation.
Sublimation is a thermal process of state or phase change in which solid substance is directly converted into gas without melting i.e the substance won't undergo liquid state.
In the given question, dry ice is given. Dry ice is the solid state of carbon dioxide. When the dry ice changes to carbon dioxide, directly solid carbon dioxide is converted into gaseous carbon dioxide. No liquid carbon dioxide is formed . So, the phase change is from solid to gas.
Hence, the conversion of dry ice into carbon dioxide is an example of sublimation.
Answer: The coefficient of friction is 0.35
Explanation:
We can write the friction force as:
F = N*μ
Where N is the normal force between the refrigerator and the ground, as the full weight of the refrigerator is acting on the ground, the normal force will be exactly equal to the weight of the refrigerator, then:
N = 650N
And μ is the coefficient of friction.
And for this case, the force is 230N, then we have:
F = N*μ
230N = 650N*μ
(230N/650N) = μ = 0.35
Notice that the distance did not matter for this calculation.