Which of the following reactions have a positive ΔSrxn? Check all that apply.?

I think you mean entropy

For entropy to be positive solids should be turned into liquid or gases.

In gases

Moles of gaseous products > Moles of gaseous reactants

For reaction

1st reaction – Entropy is positive (moles of products > Reactants)

2nd reaction – Entropy is positive (solid is turned into gas)

3rd reaction – Entropy is negative (moles of products < reactants)

4th reaction – Entropy is negative (moles of products < reactants)

So you want something that is more discorded.

So this is solids turning to liquids and liquids turning to gasses

or 1 mole of gas turning into two moles of gas ect.

A(s)+B(s)—->C(g)

Solids turning to gas so more disorder, positive delta S