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.: 
 
        
             
        
        
        
Answer:
An innate, typically fixed pattern of behavior in animals in response to certain stimuli.
 
        
             
        
        
        
Answer:
These two numbers are fixed for an element. The mass number tells us the number the sum of nucleons of protons and neutrons in the nucleus of an atom. The atomic number also known as the proton number is the number of protons found in the nucleus of an atom. ... The atomic number uniquely identifies a chemical element.
Explanation:
 
        
             
        
        
        
Answer:
Option A. the hydroxyl group (-OH) 
Explanation:
Ethanol, CH₃CH₂OH belongs to the class of organic compound called alkanol. 
They have general formula as R–OH
Where 
R => is an alkyl group
OH => is the hydroxyl group
The hydroxyl group (OH) is the functional group of the alkanol (alcohol) 
 
        
             
        
        
        
An Endothermic change is a process in which there is absorption of energy. 
-Condensation is the transformation from a gas to a liquid. So the water molecules releases energy while condensing, so condensation is exothermic (opposite of endothermic, it's the release of energy)
-Vaporization is the transformation from a liquid to a gas. When you heat water to evaporate it, you're giving energy to the water molecules. And when they absorb this energy, they transform to a gas. Which means that Vaporization is endothermic. 
-Deposition is the transformation from gas directly to solid without passing by the liquid phase. Same as the condensation, but the water molecules release even more energy to directly become Solid. So deposition is exothermic.
-Freezing is the transformation from a liquid to a solid. During this phase, water molecules releases energy to its surrounding. So freezing is exothermic.
We can conclude that Vaporization is endothermic, because it's absorbing energy to transform from liquid to gas, while condensation, deposition and freezing are exothermic because they release energy to transform.
Hope this Helps! :)