Radioactive material obeys 1st order decay kinetics,
For 1st order reaction, we have
k =

where, k = rate constant of reaction
Given: Initial conc. 100, Final conc. = 6.25, t = 18.9 hours
∴ k =

= 0.1467 hours^(-1)
Now, for 1st order reactions: half life =

= 4.723 hours.
The element aluminum forms a cation with the charge of +3. The symbol for this ion is Al³⁺, and the name is aluminum ion. The number of electrons in this ion 10.
<h3>What are ions?</h3>
Ions are formed when an atom gains or loses electrons.
Metals form positive ions by a loss of electrons whereas non-metals form negative ions by gaining electrons.
The aluminum ion is formed when aluminum loses three electrons to form Al³⁺ ion which has 10 electrons.
in conclusion, ions are formed by a gain or loss of electrons.
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Answer:
A rock is an inconsistent mixture of minerals, while mineral is "pure" and made up of a precise combination of chemicals.
Explanation:
Answer:
The molecules absorb heat and acquire more kinetic energy.
Explanation:
In a solid, the solids only vibrate about their mean positions but do not translate. When energy is supplied to the molecule in the form of heat, the molecules vibrate faster. Eventually, they acquire sufficient energy to leave their mean positions and translate. Hence the solid crystal collapses.
When ice is heated, water molecules acquire sufficient kinetic energy to translate. The intermolecular bonds are gradually broken in the solid framework as heat is absorbed. The heat required for this is known as the latent heat of fusion.
The temperature remains constant until phase transition is over, then temperature rise resumes.