If you could build a new device that would help the world (or just you personally) what would you design? Explain what you would build, how it would work, and how it would be useful to society

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock

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