Answer:
Explanation:
A physical change is a change in which the physical properties of matter are altered. These are properties are the forms and state.
Most physical changes are easily reversible and are pure state changes.
They do not lead to the production of new compounds.
They involve no mass change and requires little to no energy.
Examples are melting, boiling, freezing, sublimation e.t.c
Answer:
The rates of decay of radioactive elements
Explanation:
The age of a rock in years is called its absolute age. Geologists find absolute ages by measuring the amount of certain radioactive elements in the rock. When rocks are formed, small amounts of radioactive elements usually get included.
Answer:
It heats up.
Explanation:
Because thermal energy is based off the temperature of an object and the average kinetic energy of its particles increases. When the average kinetic energy of its particles increases, the object's thermal energy increases. Therefore, the thermal energy of an object increases as its temperature increase.
Answer:
H₂Se
Explanation:
A way of estimating the acidity of a weak acid is by analizing the<em> stability of the formed anion</em>. In this case, we should find a Group 6A element that in its anionic forms (HX⁻ and X⁻²) is more stable than HS⁻ and S⁻², thus it would be more acidic in aqueous solution.
The anionic forms of Se are more stable than the forms of S, similarly to how Br⁻ is more stable than Cl⁻.
