The Sand Skink get its water from maybe lakes, rivers, or ponds i believe.
Yes it has legs. They are vestigial (not fully formed) and practically useless.
yes
No. The water is in the sand.
No - they require completely different habitats !
A female isn't coloured whereas a male has a red,yellow,blue or green chest.
A skink lives in a rainforest
No, Frogs do not need sand to live in the water. Frogs though may elect to live in swim in sand many are just as happy to bury themselves in small pebbles, mud, or other fine substrate. This practice is to hide from predators such as snakes. If there is no predators, or species that the frog views as a potential predator, a frog will be fine to leave in the water with no substrate at all. Though the frog is safe and can survive this will likely cause the animal stress. Simply to answer in a line all frogs need to survive is a source of oxygen and a source of food, not sand.
Water from sand is evaporated.
the variable skink is a reptile
no they can not
skink is singular skinks is plural.
Sand is not soluble in water and sand particles are settled.