a toy car is pushed forward with a force of 5N. Air resistance and friction apply a combined force of 3.5N backwards, what is the resultant force

Hi... U should do like this

5 - 3.5=1.5 (N)

indium, and thallium have three electrons i think

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