<span>The effective nuclear charge of an atom = total electrons - inner electrons
For O, ENC = 8 - 2 = 6
For Li, ENC = 3 - 2 = 1
For C, ENC = 6 - 2 = 4
The electrons in O experience the greatest effective nuclear charge and that is why O is smaller than C (which is smaller than Li).</span>
Answer:
Ethanol (boiling point 78°C) and methanol (boiling point 65°C) are two miscible liquids. There is only a small difference in their boiling points. These two liquids are separated from their mixture by fractional ths distillation.
When vapours of the mixture pass through the fractionating column, repeated liquefaction and vapourisation take place. Subsequently, the vapours of low boiling methanol enter the condenser from the fractionating column, condense to liquid and get collected in the round bottomed flask first. Similarly, ethanol with higher boiling point can be collected later in another round bottomed flask.
Answer:
Polymerase Chain reaction is a method used by scientists to making A LOT (millions to billions) of copies of a DNA sample which then allows scientists to take a small of that DNA and increase the amount to a very large amount to study the DNA into further detail.
Answer: A. It can be found on the periodic table. E. It is made of only one type of atom.
Explanation: Element is the pure substance which is made up of similar atoms and cannot be separated into its components. Example : Al
Compound is the pure substance which is made up by combination of two or more elements in a fixed ratio by mass. Example : 
A) Every element can be found on the periodic table.
B) Element can be a solid, liquid or a gas.
C) Elements can be separated into different components as it is made up of only single type of atoms.
D) Only solids have fixed shape and volume.
E) Elements are made up of only one type of atoms.
Answer:
Explanation: If the water vapor content stays the same and the temperature drops, the relative humidity increases. If the water vapor content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn't require as much moisture to become saturated as warmer air.