Entropy of the universe is

One mole of which of the following has the highest entropy?

Melting point of a solid is $x \ K$ and its latent heat of fusion is $600 \ cal \ mol^{-1}$. The entropy change for fusion of $1 \ mol$ solid is $2 \ cal \ mol^{-1} \ K^{-1}$. The value of $x$ will be......$K$

For a $Carnot$ engine,the source is at $500 \ K$ and the sink at $300 \ K$. What is the efficiency of this engine?

Calculate the sign of $\Delta S$ for the melting of ice at $275 \ K$.

Predict in which of the following,entropy increases or decreases:
$(i)$ $A$ liquid crystallizes into a solid.
$(ii)$ Temperature of a crystalline solid is raised from $0 \, K$ to $115 \, K$.
$(iii)$ $2NaHCO_{3(s)} \to Na_2CO_{3(s)} + CO_{2(g)} + H_2O_{(g)}$
$(iv)$ $H_{2(g)} \to 2H_{(g)}$