Robert A. Millikan and Harvey Fletcher performed the oil drop experiment.
Answer:
a pure substance consists only of one element or one compound
a mixture consists of two or more different substances, not chemically joined together.
examples:
pure substance : Hydrogen gas - Diamond - Gold metal.
mixture : water and oil - mixtures of sand and water - trail mix
Explanation:
Heat required : 4.8 kJ
<h3>Further explanation
</h3>
The heat to change the phase can be formulated :
Q = mLf (melting/freezing)
Q = mLv (vaporization/condensation)
Lf=latent heat of fusion
Lv=latent heat of vaporization
The heat needed to raise the temperature
Q = m . c . Δt
1. heat to raise temperature from -20 °C to 0 °C

2. phase change(ice to water)

3. heat to raise temperature from 0 °C to 25 °C


Answer : The given statement is, false.
Explanation :
Ionic product of water : It is defined as the product of the concentration of hydrogen ion and the concentration of hydroxide ion.
The mathematical expression will be,
![[H^+][OH^-]=10^{-14}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%5BOH%5E-%5D%3D10%5E%7B-14%7D)
When the concentration of hydrogen ion and hydroxide ion are equal then the solution is neutral and the value will be,
. And the pH of the solution is, 7.
When the concentration of hydrogen ion is greater than
then the solution is acidic in nature. And the pH of the solution is, less than 7.
When the concentration of hydrogen ion is less than
then the solution is basic in nature. And the pH of the solution is, greater than 7.
Hence, the given statement is false.