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.:
A is the answer
Hope it helps :)
Answer:
I think the answer is D a ray of violet light
Hope it helps!
d. exothermic; leaving
- Exothermic reaction is a reaction that produces heat in the reaction whereas the endothermic reaction is a reaction in which heat is required to be given in the reaction to produce product.
- Fire is an exothermic reaction.
- A fire is produced due to oxidation of the fuel in the form of liquid or gas.
- A fire is an example of combustion.
- In fire both heat and light are left from fire due to the oxidation of fuel.
Hence, option d. exothermic; leaving is the correct option.
Learn more about fire:
brainly.com/question/12761984
When in water, MgCl2 dissociates into magnesium ions and Cl- ions and NaOH into Na and OH ions. The equation is as follows:
MgCl2 = Mg2+ + 2Cl-
NaOH = Na+ + OH-
The initial concentrations are as follows:
[Mg2+] = .220(<span> 2.47x10^-4) / .220+.180 = 1.36x10^-4 M Mg2+
</span>[OH-] = .180 (3.52x10^-4) / .220+.180 = 1.58x10^-4 M OH-
