Which metal element is not solid at room temperature?

The hydroxides and carbonates of sodium and potassium are easily soluble in water,while the corresponding salts of magnesium and calcium are sparingly soluble in water. Explain.

Which gas/gases evolve$(s)$ when sodium metal is reacted with water at room temperature?

$KO_2$ (potassium superoxide) is used in oxygen cylinders in space and submarines because it

Four reactions are given below:
$(i)$ $2Li + 2H_2O \to 2LiOH + H_2$
$(ii)$ $2Na + 2H_2O \to 2NaOH + H_2$
$(iii)$ $2LiNO_3 \xrightarrow{\text{Heat}} 2LiNO_2 + O_2$
$(iv)$ $2NaNO_3 \xrightarrow{\text{Heat}} 2NaNO_2 + O_2$
Which of the above,if any,is wrong?

Which of the following is most soluble in water?