Answer: Option (b) is the correct answer.
Explanation:
A change that does not lead to any difference in chemical composition of a substance is known as a physical change.
For example, shape, size, mass, volume, density, boiling point, etc of a substance are all physical properties.
Boiling of water is a physical change as it leads to conversion of liquid state of water into vapor state.
On the other hand, changes that lead to bring change in chemical composition of a substance is known as a chemical change.
For example, exploding dynamite, rotting cheese etc are all chemical changes.
Thus, we can conclude that the statement no, boiling water is a physical change is true when water is heated, bubbles form in the water. This evidence is not of a chemical reaction.
Answer:
Explanation:
Mixtures are impure substances with the following properties:
- Their composition is indefinite i.e they consisit of two or more elements or compounds in any proportion by mass.
- Their constituents retains their identity i.e physical properties are retained.
- They can easily be seperated by physical methods into their constituents.
It is important to seperate materials from mixtures because mixtures do not undergo chemical changes when they combine. This implies that they can easily be seperated using simple seperation techniques with the constituents still retaining their properties.
Answer:
Explanation:
We usually approximate the density of water to about 
at room temperature. In terms of the precise density of water, this is not the case, however, as density is temperature-dependent.
The density of water decreases with an increase in temperature after the peak point of its density. The same trend might be spotted if the temperature of water is decreased from the peak point.
This peak point at which the density of water has the greatest value is usually approximated to about 
. For your information, I'm attaching the graph illustrating the function of the density of water against temperature where you could clearly indicate the maximum point.
To a higher precision, the density of water has a maximum value at , and the density at this point is exactly .
Answer:
At the plate boundary, there would be a divergent boundary where we can see a mid ocean ridge and a gap. We would be able to see the mantle because there would be a fissure from where magma will rise and solidify.
Explanation:
Under the South American plate and African plate, there are currents that cause a divergent boundary. They create this boundary since they pull the tectonic plates apart, causing a mid-ocean ridge with an opening that allows the rising of the magma that was underneath. Once that the magma is out, it solidifies, and the currents will try to create another ridge to repeat the process.
When the plates are apart, the mantle that is beneath is exposed, and we can see the magma.
It is approximately 10 ^ -10
