Answer: C) Elements and pure compounds are homogeneous materials because they have a uniform composition throughout.
Explanation: Element is a pure substance which is composed of atoms of similar elements. Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.
Elements are compounds form homogeneous materials as they have uniform composition throughout and the components are evenly distributed throughout the material.
Mixtures are heterogeneous materials as they do not have uniform composition and the components are not evenly distributed throughout the material.
I believe the answer would be 2 because, assuming the substance is water, at 50 degrees Celsius it whole be liquid, 100 degrees celsius is its boiling point and at 150 degrees Celsius water is steam.
Density can be determined as:
d = m /V
whereas, m is mass of compound
v is volume
d = 700 /840 = 0.83 g /mL
Thus density is 0.83 g /mL
The correct answer is (4) A large amount of energy is produced in a nuclear fission reaction.
Choice (1) is false, the products are radioactive, and often have to be buried underground for long periods of time. Choice (2) is false, because the reactants are often unstable to allow them to decay and release energy. Choice (3) is false, because the radioactive substances can affect living organisms.
