The correct answer is D.
Echo refers to the sound that is heard when a sound wave is reflected back from a surface. An echo sound is made when a sound wave traveled through the air, hit a hard surface and get reflected back. Generally, hard surfaces reflect sound wave while soft surfaces absorb sound waves. Reflected sound waves are used in application of some devices that are used in range and direction finding.
The phase diagram of CO2 has a melting curve that slopes up and to the right, in contrast to the phase diagram of water, which has a more conventional shape. It is impossible for liquid CO2 to exist at pressures lower than 5.11 atm because the triple point is 5.11 atm and 56.6 °C.
Due to the fact that ice is less thick than liquid water, the phase diagram of water has an odd melting point that drops with pressure. Carbon dioxide cannot exist as a liquid at atmospheric pressure, according to the phase diagram of the gas. Thus, gaseous carbon dioxide directly sublimes from solid carbon dioxide.
Learn more about solid carbon dioxide.
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Because of differences in molecular structure, the empirical formula remains different between hydrocarbons; in linear, or "straight-run" alkanes, alkenes and alkynes, the amount of bonded hydrogen lessens in alkenes and alkynes due to the "self-bonding" or catenation of carbon preventing entire saturation of the hydrocarbon by the formation of double or triple bonds.
<span>This inherent ability of hydrocarbons to bond to themselves is referred to as catenation, and allows hydrocarbon to form more complex molecules, such as cyclohexane, and in rarer cases, arenes such as benzene. This ability comes from the fact that bond character between carbon atoms is entirely non-polar, in that the distribution of electrons between the two elements is somewhat even due to the same electronegativity values of the elements (~0.30), and does not result in the formation of an electrophile.
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Potassium ......................