Answer: b. One atom transferring electrons to another atom
Explanation: An ionic bond is formed when an element completely transfers its valence electron to another element. The element which donates the electron is known as electropositive element and the element which accepts the electrons is known as electronegative element. This bond is formed between a metal and an non-metal.
Covalent bonds are formed by sharing of electrons between non metals
For example, In calcium iodide the one electron from calcium metal gets transferred to iodine atom and thus form an ionic bond to give 
Electronic configuration of calcium:
![[Ca]=1s^22s^22p^63s^23p^64s^2](https://tex.z-dn.net/?f=%5BCa%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E64s%5E2)
Calcium atom will lose two electron to gain noble gas configuration and form calcium cation with +2 charge.
![[Ca^{2+}]=1s^22s^22p^63s^23p^6](https://tex.z-dn.net/?f=%5BCa%5E%7B2%2B%7D%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E6)
Electronic configuration of iodine:
![[I]=1s^22s^22p^63s^23p^64s^23d^{10}4p^5](https://tex.z-dn.net/?f=%5BI%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E64s%5E23d%5E%7B10%7D4p%5E5)
Iodine atom will gain one electron to gain noble gas configuration and form iodide ion with -1 charge.
![[I^-]=1s^22s^22p^63s^23p^64s^23d^{10}4p^6](https://tex.z-dn.net/?f=%5BI%5E-%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E64s%5E23d%5E%7B10%7D4p%5E6)
I believe it to be C
Explanation: The concentration of carbon dioxide in Earth’s atmosphere is currently at nearly 412 parts per million (ppm) and rising. This represents a 47 percent increase since the beginning of the Industrial Age, when the concentration was near 280 ppm, and an 11 percent increase since 2000, when it was near 370 ppm.
Answer:
The correct answer is - so that other scientists can replicate the experiment and make sure the results are correct or to check accuracy.
Explanation:
The data and procudres are required to be recorded or noted correctly so the experiment and research can be replicate and tested for the accuracy of the experiment by other scientist and researcher.
Mandy also need to note procedure, data, variables and other data correctly for the testing the accuracy and replication of the experiment. The replication is essential to check if every thing is correct and result are error free.
Chemical reactions convert reactants to products, whose properties differ
from those of the reactants. Chemical equations are a compact and
convenient way to represent chemical reactions. They have the general form
Reactant(s) → Product(s)
The arrow in the equation means "changes to" or
"forms." The reaction of gaseous nitrogen with hydrogen to
produce ammonia, NH
3
, is represented by the chemical equation
Although there are thousands of chemical reactions, a significant number
of them, especially those that are not organic reactions, can be
classified according to four general patterns: combination, decomposition,
displacement, and exchange.
Read more: http://www.chemistryexplained.com/Di-Fa/Equations-Chemical.html#ixzz4XjnDFUrK
<span>Heat would make the molecules move faster so they would spread out therefore making air less dense.
Less dense means less packed. Heat increase the kinetic energy</span>
