How much energy is absorbed when a 50.0 gram magnesium strip is heated from 45 degrees to 90 degrees

Quantity of heat energy required for change of phase= (mass) x (heat of fusion or heat of vaporization), or in equation form Q=mL. Heat of fusion=80cal/g; heat of vaporization=540 cal/g
quanity of heat energy responsible for a temperature change= (mass) x (specific heat) x (change in temperature), or in equation form,  Q=mcT

Here's another way to calculate it  

Calculate the energy absorbed by 20 grams of 100 C water that is turned into 100 C steam
Q=(20g)(540 cal/g)=10,800 cal 

I hope this helps you.

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic 

Answer : option c) heat is released during the process.explanation :

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.