Answer:
The spectra of the Sun and stars exhibited bright and dark lines called Fraunhofer lines. These were shown to be caused by elements emitting or absorbing light at specific wavelengths. Because each element emits or absorbs light only at specific wavelengths, the chemical composition of stars can be determined.
Answer: The correct option is D.
Explanation: Nonmetallic minerals are the chemical elements from which no new product can be formed when they are melted. For Example: Sand, marble etc..
For the given options:
Option A: Wood is a type of cellulose and is not considered as a nonmetallic mineral resource.
Option B: Iron is an element because it is the smallest substance which cannot be broken down. It is not considered as a nonmetallic mineral resource.
Option C: Coal is a mixture of carbon compounds. This is very close to mineral but is an organic mineral because it contains carbon atom. Hence, it is not considered as a nonmetallic mineral resource.
Option D: Aggregate is formed by the collection of particles forming a whole mass. This is a non-metallic resource as it cannot form any new product.
Hence, the correct option is D.
Virtual and enlarged..............
What grade are you in btw ?
Answer:
Air pressure is what you measure with a tire gauge. Atmospheric pressure is what you measure with a mercury barometer. ... Pressure is the amount of force per unit area that a gas exerts on a surface
Explanation:
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