Which of the following processes have a ? s > 0?

2hcl(g) ? h2(g) + cl2(l)
2nh3(g) + co2(g) ? nh2conh2(aq) + h2o(l)
lithium fluoride forms from its elements
cesium chloride dissolves in pure water
all of the above processes have a ? s > 0

Cesium chloride dissolves in pure water has > 0.

Explanation:

Entropy is the measure of randomness or disorder of a system. If a system moves from  an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

is positive when randomness increases and is negative when randomness decreases.

a)

As 2 moles of gas are converting to 1 mole of gas and 1 mole of liquid, the randomness decreases and hence is negative.

b)

As gas molecules are converting into aqueous and liquid form,  the randomness decreases and hence is negative.

c) lithium fluoride forms from its elements:

As elements are combining to form a compound, the randomness decreases and hence is negative.

d) Cesium chloride dissolves in pure water :

As compound is dissociating into ions, the randomness increases and hence is positive.