Explanation:
A physical change is a change that alters the physical properties of matter most especially the state and the form. This change has the following attributes.
- it is easily reversible
- leads to the production of no new kinds of matter
- involves no change in mass
- requires little energy
Therefore, some of the examples of physical changes are:
- boiling
- melting
- freezing
- condensation
- sublimation
- magnetization of metals
- breaking of glass
- cutting of wood
The theory of evolution was proposed by Darwin.
Explanation:
substance Q could be <em><u>oxygen (O2)</u></em>
substance R could be <em><u>carbon</u></em><em><u> </u></em><em><u>d</u></em><em><u>i</u></em><em><u>o</u></em><em><u>x</u></em><em><u>i</u></em><em><u>d</u></em><em><u>e</u></em><em><u> </u></em><em><u>(</u></em><em><u>C</u></em><em><u>O</u></em><em><u>2</u></em><em><u>)</u></em>
The amount of substance present in a certain object with a given half-life in terms of h can be expressed through the equation,
A(t) = (A(o))(0.5)^(t/h)
where A(t) is the amount of substance after t years and A(o) is the original amount. In this item we are given that A(t)/A(o) is equal to 0.89. Substituting the known values,
0.89 = (0.5)(t / 5730 years)
The value of t from the equation is 963.34 years.
<em>Answer: 963 years</em>
