When designing a new steam power plant a colleague suggests that the efficiency and hence operational profits of the plant could be improved by adding a series of open feedwater heaters. do you agree with this statement?
a. yes they would improve efficiency and mixing chambers should not substantially increase cost or maintenance
b. no only closed feedwater heaters would increase efficiency, but they would be more expensive
c. yes they would improve efficiency but using only closed feedwater heaters would require no feedwater pumps and hence be more cost effective
d. yes but a combination of closed and open feedwater heaters would be more economical

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.

the answers are

c and c

if the temperature drops and becomes cool

then the atmosphere can be freezing as the water vapor in the air is at maximum (100%) and can be severely cold

also can be snowing lightly as the moisture in the air will start to solidify

and btw this is not chemistry but