Question

Funnel-shaped mouth of a volcano is called _______ ?
a. Vent
b. Crater
c. Chamber
d. Lavas

Answer 1

Hint:
 Due to volcanic crater volcanic activity, there is a spherical depression. This is usually a basin, in which there is a circular in the form, within which there is a vent, from which the magma explodes in the form of gases and lava. A crater can be of big dimensions and sometimes big depth.


Complete solution:
A volcano is a cavity or hole through which lava, ash, gas and water vapour emerge. Volcanic activity can range from the formation of magma and gas in the interior of the earth to the appearance of lava below and above the earth's surface and as an explosive or cracking eruption of cold and solid. Explosive emissions are seen in volcanoes when the magma is high in silica, while the silica content is usually quiet when the volume is low.

Currently, magma and lava and igneous rocks are classified on the basis of chemical and mineral composition. Minerals are divided into two categories of light colour and dark colour. Light coloured minerals are called felsic and dark coloured minerals are called mafic. In the 'felsic' group the silica predominant minerals are quartz and felspar prominently, while in the 'mafic' group, the minerals rich in magnesium and iron content are pyroxenes, amphiboles and olives. Minerals with intermediate properties of felsic and mafic are called 'ultramafic'. It contains a high amount of silicon and aluminium. Granite, diorite, and gabbro under felsic, ultramafic and mafic are examples of endogenous lava and rhyolite, andesite and basalt, respectively, are exogenous lava.

The crater is a fungal spherical shape commonly found above a volcanic cone. If water is filled in it, then the crater lake is formed, like Lonar lake in Buldhana district of Maharashtra. Sometimes many small craters are formed in the main crater. This occurs when the next ejection is of lower intensity than the previous ejection. Such a crater is called a nested crater. For example, three small craters are found in Mount Tal of the Philippines. in comparison.


Hence, the correct answer is option B.

Note:
This type of topography is formed when the lava emanating from the volcanic eruption is highly acidic and silicic, in such a situation that a hard strip of lava gets deposited in the volcanic canal and crater. If the volcano's cone hole is filled with volcanic lava, it is called a 'volcanic plug' or 'lava dot'. The lava strip deposited in the tube is called 'volcanic cervix'. The consolidated form of these two sites is called a 'diatreme'. 'Ship Rock' is an example of a diatreme in New Mexico, United States, while 'Black Hills' and 'Devil Tower' are examples of the cervical cervix in the same province. All these landforms are made in order of calm of the volcano.