Answer:
Gneiss forms by regional metamorphism from both high temperature and pressure. Quartzite and marble are the most commonly used metamorphic rocks.
The statement that best describes a solution is the option C: a mixture having a uniform composition where the components cannot be seen separately and all components are in the same state.<span> That is exactly what a solution is: a homogeneous mixture, the composition is uniform, but it can vary from one solution to other. The components must be in the safe phase, but it can be any phase: solid, liquid or gas. The most classical and clear example is the salt solution, NaCl. When you dissolve a spoon of NaCl in water you will not be able to distinguish nor separating the solute from the solvent, and the mixture will have uniform composition.</span>
Answer : The molal freezing point depression constant of X is 
Explanation : Given,
Mass of urea (solute) = 5.90 g
Mass of X liquid (solvent) = 450.0 g
Molar mass of urea = 60 g/mole
Formula used :
where,
= change in freezing point
= freezing point of solution = 
= freezing point of liquid X= 
i = Van't Hoff factor = 1 (for non-electrolyte)
= molal freezing point depression constant of X = ?
m = molality
Now put all the given values in this formula, we get
![[0.4-(-0.5)]^oC=1\times k_f\times \frac{5.90g\times 1000}{60g/mol\times 450.0g}](https://tex.z-dn.net/?f=%5B0.4-%28-0.5%29%5D%5EoC%3D1%5Ctimes%20k_f%5Ctimes%20%5Cfrac%7B5.90g%5Ctimes%201000%7D%7B60g%2Fmol%5Ctimes%20450.0g%7D)
Therefore, the molal freezing point depression constant of X is
Specific heat is the quantity of heat required to change the temperature of 1 gram of a substance by 1 degree Celsius. It is the amount per unit mass that is required to raise the temperature by one degree Celsius. Every substance has its own specific heat and each has its own distinct value. The units of specific heat are joules per gram-degree Celsius (J/f C) and sometimes J/Kg K may also be used.
Answer:
The reflection of sound waves
Explanation:
An echo is a reflection of sound that bounces of of one thing to another.
