What is magma?
a. the molten mixture of rock-forming substances, gases, and water from the mantle..
c. hardened lava on the surface of the earth.
b. liquid rock that reaches the surface.
d. all of the above?

Answer : The correct option is, (a) the molten mixture of rock-forming substances, gases, and water from the mantle.

Explanation :

Magma : It is the molten or the semi-molten state or a mixture of natural material, gases and the water from which all igneous rocks are formed.

Magma is very hot liquid rock that is found below the surface of the earth. When it flows onto the surface of the earth then it is called as lava. There are three types of magma which are basaltic, andesitic and the rhyolitic.

The formation of magma from the melting solid rocks is controlled by the three parameters which are pressure, temperature and compositions.

Hence, the correct option is, (a) the molten mixture of rock-forming substances, gases, and water from the mantle.

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.