Do frogs have two lungs?

Hint: Frogs are cold blooded amphibians belonging to the order Anura. The skin of the frogs contains no scales or hair. They intake oxygen from either water or air. They produce mucus which makes the skin stay wet and slippery. The mode of respiration is through skin, lungs and lining of the mouth. The lungs of the frogs are usually smaller in size since they have multiple ways for breathing.

Complete answer:
Frogs do not have two lungs. They have only one pair of lungs which are absent when they are born and develop later on in their life.
The baby frogs or tadpoles use gills just like those of fish. Tadpoles take in water and absorb oxygen in the water through tiny blood vessels in their external gills. The absorbed oxygen directly enters into the bloodstream. Similarly, carbon dioxide exits the tadpoles through gills. The gills will slowly vanish as the lungs of the tadpoles develop for use.
Adult frogs have lungs that breathe in oxygen. However, they are poorly developed compared with those of other vertebrates. This does not affect the frogs as the lungs are not their main method of respiration.

Note:
Frogs also breathe using their skin and the mouth lining. When they use their skin to breathe, it’s called cutaneous respiration. The skin of the frog is thin and filled with tiny blood capillaries. These capillaries secrete mucus to keep the skin moist. When the frogs are out of water, moist skin is necessary because the air diffuses into the mucus and enters the skin through the capillaries. The mouth lining also works in the same way.