For #1, I'd say it's "It will usually bond to multiple atoms which can provide a total of 4 additional electrons."
2. Ionic (I'm quite certain because anions/cations (-1 & +1) are Ionic from what I recall, if that's true it's Ionic.
3. "comparison of the associated families to which the elements belong" and
"the difference in electronegativities" are what I would choose, as I mentioned in a comment earlier.
If I'm wrong let me know, but I am at least 80% sure that these responses are correct from what I remember in Chemistry.
Answer:
Fill in the blanks with the correct term.
a. a liquid that dissolves another substance.
b. a chemical that is dissolved.
c. a value used to describe the amount of one substance dissolved in another.
d. a liquid consisting of one substance dissolved in another.
Explanation:
a. A liquid that dissolves another substance is called the solvent.
b. A chemical that is dissolved solute.
c. A value used to describe the amount of one substance dissolved in another is called concentration.
d. A liquid consisting of one substance dissolved in another is called a solution.
<>"One such trend is closely linked to atomic radii -- ionic radii. Neutral atoms tend to increase in size down a group and decrease across a period. When a neutral atom gains or loses an electron, creating an anion or cation, the atom's radius increases or decreases, respectively."<>
Carbon-14 is radioactive isotope of carbon.
Carbon is essential element of living cells. While the living cells are alive, the carbon contained in them are in equilibrium with the carbon in atmosphere. But, once the cell dies, the carbon-14 isotope undergoes radioactive decay. By measuring the carbon-14 in atmosphere to the carbon-14 in dead organism, we can calculate the time (or years) that organism have died.
However, carbon-14 dating technique is not accurate for estimating the age of materials older than 50,000 years old (above 40,000 years). This is because, 99% of carbon is carbon-12, 1% is carbon-13 and trace remaining is the carbon-14. This means, carbon-14 is found in very trace amount, in fact 1 part per trillion of carbon atoms present is carbon-14. The half of life of carbon-14 is 5,730 years. For dating the organism, we use the concept of half lives of the carbon-14 isotope in the dead organisms and calculate how many half life old the sample is. But as the years increases, the number of carbon-14 isotope becomes too low to detect and make accurate calculation.
This means, at some point the organism can simply run out of carbon-14.
Hence carbon-14 dating is not accurate for estimating age of materials older than 50,000 years old.
<u>Answer:</u> The correct answer is Option A.
<u>Explanation:</u>
Standard enthalpy of formation is the change in enthalpy of one mole of a substance present at the standard state that is 1 atm of pressure and 298 K of temperature. The substance is formed from its pure elements under the same conditions.
We are given a chemical compound having chemical formula 
This compound is formed by the combination of calcium, nitrogen and oxygen elements.
The chemical equation for the formation of from the components in their standard states follows:
Hence, the correct answer is Option A.
