(b) Huiting wanted to find out the hardness of two materials H and F. She used a
rounded object made of material G and forced it into each material with the
same force. The results of her experiment are shown below.
rounded object of
material G
rounded object
of material G
3 mm
1 mm
object of
material H
object of
material F
List materials F, G, H in increasing order of hardness. Explain your answer.
[2]

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.

the answer is c i took the test

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