Final answer:
The statement is false. A volcanic mountain with gently sloping sides formed from basaltic lava flows is a shield volcano. A cinder cone is a volcano composed of small fragments of lava ejected from a single vent.
Step-by-step explanation:
The statement given in the question, 'A volcanic mountain with gently sloping sides built almost entirely out of basalt lava flows is called a cinder cone' is False.
A volcanic mountain with gently sloping sides formed from basaltic lava flows is typically referred to as a Shield Volcano. Examples of these include the Hawaiian Islands. They are characterized by their large size and gentle sloping sides, which are due to the low viscosity of the basaltic lava allowing it to flow quickly and over long distances. The lava cools and solidifies, gradually building up the size of the volcano over many eruptions.
In contrast, a Cinder cone, also known as a scoria cone, is a different type of volcano. These are typically smaller, with steep sides, and are made up of small fragments of lava ejected from a single vent and cooled quickly in the air before falling back to the ground.
Learn more about Volcanic Mountains