Which example shows electrical energy being transformed into heat energy?
a) burning a wax candle
b) a small toaster oven toasts a bagel
c) rubbing two sticks together
d) sunlight heating a metal door

B (a small toaster oven toasts a bagel)

Explanation:

(a) Burning of a wax candle is an example of transformation of chemical energy to heat energy since the wax is made up of hydrocarbons.

(b) small toaster oven roasting a bagel is an example of electrical energy transforming or converting into heat energy since the toaster requires electrical energy in form of electricity to convert it into heat energy in the presence of a thermostat.

(c) rubbing two sticks together is an example of heat energy transforming or transformed into electrical energy by producing static currents.

(d) sunlight heating a metal door is am example of light energy transformed into heat energy through reflection of sun rays, the metal door absorbs heat and gets warmed.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol