Answer:
The right choice is c. Water molecules have a weakly positive hydrogen end.
Explanation:
The unequal sharing of electrons in water molecule gives a slight negative charge near its oxygen atom ( see image below) and a slight positive charge near its hydrogen atoms. A neutral molecule that has a partial positive charge at one end and a partial negative charge at the other, it is a polar molecule.
so
a. Water molecules have a nonpolar bond.
It is wrong choice because water has polar bond .
b. Water molecules have a weakly positive oxygen end.
Also, a wrong choice due to water molecule gives a slight negative charge near its oxygen atom.
c. Water molecules have a weakly positive hydrogen end.
This is the right choice.
d. Water molecules have two oxygen and two hydrogen atoms
It is wrong choice because water has one oxygen and two hydrogen atoms
<u>So, the right choice is</u>
c. Water molecules have a weakly positive hydrogen end.
Answer:
b) Counter current
Explanation:
In mechanical, chemical, nuclear and other systems, it happens that heat must be transferred from one place to another or from one fluid to another. Heat exchangers are the devices that allow you to perform this task the types of exchangers are presented of heat as a function of flow: parallel flow; <u>counterflow</u>; cross flow.
Among the main reasons why exchangers are used
Heat are as follows:
• Heat a cold fluid using a fluid with a higher temperature.
• Reduce the temperature of a fluid by means of a fluid with a lower temperature.
• Bring the fluid to the boiling point using a fluid with a higher temperature.
• Condense a fluid in a gaseous state by means of a cold fluid
A backflow occurs when the two fluids flow in the same direction but in opposite way. Each of the fluids enters the exchanger through different ends Since the fluid with less temperature goes backflow from the heat exchanger at the end where the fluid enters with higher temperature, the temperature of the coldest fluid will approach the temperature of the inlet fluid.
This type of exchanger turns out to be more efficient than the other two types mentioned above. In contract with the exchanger parallel flow heat, the counterflow exchanger may have the highest temperature in the cold fluid and the lower temperature in the hot fluid after heat transfer in the exchanger.
<em>
Be careful with </em><u><em>turbulent</em></u><em> that it is not a type of exchanger but a system in which a fluid is found.</em>
