Fractional distillation<span> is essentially the same as </span>simple distillation<span>except that a fractionating column is placed between the boiling flask and the condenser. The fractionating column is usually filled with glass or plastic beads. These beads improve the separation between the liquids being </span>distilled<span>.</span>
Answer: Option 1 and 11
1. Organic solvents are often flammable.
II. Organic solvents are often toxic.
Explanation:
Organic solvents are often flammable and Organic solvents are often toxic are the reasons why organic chemistry is a primary target of green chemistry because green chemistry is the use of principles or approach to remove hazardous or toxic substances from chemical.profuctd or processes to make them fit or safe for use and the solvents of organic chemist are toxic, therefore green chemistry remove the toxic substances.
Answer: a) 
b) 
c) 
d) 
Explanation:
General representation of an element is given as:_Z^A\textrm{X}
where,
Z represents Atomic number
A represents Mass number
X represents the symbol of an element
Mass number is defined as the sum of number of protons and neutrons that are present in an atom.
Mass number = Number of protons + Number of neutrons
In an atom, when neutrons or protons are lost or gains, it directly affects the mass number of an atom.
Atomic number is defined as the number of protons or number of electrons that are present in an atom.
It is characteristic of a particular element.
Atomic number = Number of electrons = Number of proton
a) Z 74, A 186: 
b) Z 80, A 201: 
c) Z 34, A 76: 
d) Z 94, A 239.: 