The correct order of increasing solubility in water is

Which of the following is Potash Alum?

Fill in the blanks:
$(1)$ ......... method is used to prepare sodium carbonate.
$(2)$ Sodium carbonate exists as .........
$(3)$ Sodium chloride is commonly known as .........
$(4)$ Sodium chloride melts at ......... temperature.

Which of the following elements liberate $H_2$ gas on reaction with $NaOH$?

$A$ certain metal $M$ is used to prepare an antacid,which is used as a medicine for acidity. This metal accidentally catches fire,which cannot be extinguished by using $CO_2$ based extinguishers. The metal $M$ is

What type of oxides do alkali metals form? Discuss some of the physical properties of these oxides.