The melting of solid wax to form liquid wax and the evaporation of liquid wax to form wax vapor are physical changes. The burning of the wax vapor is a chemical change.
It takes 33.4 s for the concentration of A to fall to one-fourth of its original value.
A <em>half-life</em> is the time it takes for the concentration to fall to half its original value.
Assume the initial concentration is 1.00 mol/L. Then,
The concentration drops to one-fourth of its initial value in two half-lives.
∴ Time = 2 × 16.7 s = 33.4 s
Answer:
B. 3+
Explanation:
When Fe²⁺ loses an electron, it becomes an Fe³⁺ ion.
The loss of an electron in an atom makes the atom becomes positively charged. Further losing electrons makes the atom more positive.
For the given ion;
Fe²⁺ if it loses an electron more, it becomes Fe³⁺.
The expression is given as:
Fe²⁺ → Fe³⁺ + e⁻
In a liquid, particles are close together but can move in any direction. They won't keep a definite shape like solids do.
3Fe(s) + 4H2O(l) — 1Fe3O4(s) + 4H2(g)
