<span>C4H10 + 6.5 O2 ----> 4CO2 + 5H2O
2C4H10 + 13 O2 ----> 8CO2 + 10H2O
1. Count the C on the left (4), put a 4 where the C on the right.
2. Count the H on the left (1), you have two on the right, so you multimply this two by 5. Put the 5 in front of the H2O
3. Count the O on the right. You have 4*2 + 5 = 13. You have two on the left, so you need 6.5 on the left.
4. Now multiply everything on the equation by two so you have nice integer numbers.
5. check you have the same amount of everything on each side.
Example C: left 8, right 8, etc.
I hope this helps. :)</span><span>
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Answer:
substances with a higher boiling point are returning back to the flask which allows another substances with the specific context temperature (lower boiling point) to boil over and be purified.
Explanation:
The reason it happens because the lower boiling point substance vaporizes and crosses over while the other substance is waiting for its boiling point to reach
Within a physical change, an element can change forms, such as going from solid to a liquid through melting. Color change can also occur during a physical change. Physical changes are very different from chemical changes. In a chemical change the element itself changes into something else within a reaction, such as combustion (burning).
Hope this helped
Answer:

Explanation:
The question will be easier to solve if we interpret it as, " How long will it take until one-fourth of a sample of the element remains,?"
The half-life of the element is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:


Electronic configuration of cromium is
Cr-[Ar]4s¹3d⁵
When cromium loses two electrons it becomes Cr⁺².
So its electronic configuration becomes,
Cr⁺²-[Ar]3d⁴
One electron will go from 4s orbital and one electron will go from 3d orbital.
So the answer here is D. [Ar]3d⁴ -because after losing 2 electrons electronic configuration of cromium becomes [Ar] 3d⁴.