Express the sum of 9.78 g and 7.0 g using the correct number of significant
digits.

C. 16. 8 g

Explanation:  

when we are using significant numbers we have to keep in mind if the last digit is over 5 or down 5 to increase or decrease 1 digit the number to the left, if the last number is down 5, we decrease the number to the left 1 digit, but if the number is over 5, we can increase 1 digit to the number to left.

then we have this equation, as the 0 is not a significant number, we can omit this one.

9.78 g + 7.0 g = 16.78 g

as the last number is over 5 we can increase 1 digit to the number to the left, the we get the following result.

16.78 g = 16.8 g

because of that the correct answer is C. 16. 8 g

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.

gasoline is a mixture. it contains several different kinds of compounds that can be present in a variety of ratios.