A chemist is studying an unknown substance and could break the substance into its elemental components only by using chemical means. Based on this observation, how should the unknown substance be classified? A. impure substance
B. solution
C. mixture
D. pure substance

The correct option is D.

In chemistry, a pure substance refers to a matter that possesses definite and constant composition with unique chemical properties. Another word for a pure substance is chemical substance. A pure substance typically contains only one type of atom or only one type of molecule. Examples of pure substances are water, sodium chloride, gold, silver, etc. In the question given above, we are told that the unknown element can only be broken down by chemical mean, this shows that the unknown compound is a chemical compound.

Explanation:

-first use of geothermal energy occurred more than 10,000 years ago in north america by american paleo-indians

-the first industrial use of geothermal energy began near pisa, italy in late 18th century

-in 1904, italian scientist piero ginori conti invented the first geothermal electric power plant in which steam was used to generate the power

-with the above experiment, the first geothermal plant in usa started in 1922 with a capacity of 250 kilowatts

-however, in 1946 first ground-source geothermal heat pump installed at commonwealth building in portland, oregon

-during the 1960’s, pacific gas and electric began operation of first large scale geothermal power plant in san francisco, producing 11 megawatts

-in 1973, when oil crisis began many countries began looking for renewable energy sources and by 1980’s geothermal heat pumps (ghp) started gaining popularity in order to reduce heating and cooling costs

-as effect of climate change started showing results, governments of various countries joined hands to fight against it, for which kyoto protocol was signed in japan in 1997, laid out emission targets for rich countries and required that they transfer funds and technology to developing countries, 184 countries have ratified it

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jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.