Metals are lustrous, malleable, ductile, good conductors of heat and electricity. Other properties include: State: Metals are solids at room temperature with the exception of mercury, which is liquid at room temperature
Answer: Two answers apply to physical change:
1-Condensation of Ethanol
2-Evaporation of Ethanol
Explanation:
Physical and Chemical changes are two very different types of change. However, both processes are possible because of the same thing: the investment of energy.
Physical change requires a lower investment of energy and this is the reason why these kind of changes can be reverted and the molecular structure of the matter does not change.
For example: I can easily change the state of water with fire or a fridge, and go from ice to liquid to vapor and back as many times I want. This is possible because I'm not giving enough energy to break or modify bonding forces inside the molecule of water, but enough energy to modify the interaction between two different molecules of water.
This is why Ethanol can be evaporated and then condensated into liquid again, representing this physical changes.
Chemical change, on the other hand, requires a higher investment of energy and because of this is that the bonds between atoms inside a molecule can be affected (bonds between atoms in the molecule are stronger). Therefore, when the molecules themselves are modified, the matter is transformed from a compound into a new one. This is why glucose becomes carbon dioxide, ethanol or carbon. These three compounds appear when the bonds between Carbons in the glucose are broken.
Answer:
The new moles of the gas in the flask is 2.13 moles.
Explanation:
Given;
number of moles of gas, n = 1.9 mol
temperature of the gas, T = 21 °C = 21 + 273 = 294 K
pressure of gas, P = 697 mmHg
volume of gas, V = ?
Apply ideal gas law;
PV = nRT
Where;
R is gas constant, = 62.363 mmHg.L / mol. K
V = nRT / P
V = (1.9 x 62.363 x 294) / 697
V = 49.98 L
New pressure of the gas, P = 795 mmHg
New temperature of the gas, T = 26 °C = 273 + 26 = 299 K
New moles of the gas, n = ?
Volume of the gas is constant because volume of the flask is the same when more gas was added.
n = PV / RT
n = (795 x 49.98) / (62.363 x 299)
n = 2.13 moles
Therefore, the new moles of the gas in the flask is 2.13 moles.
The correct answer is A. A test tube of zinc oxide. Zinc oxide is a compound which is a pure substance composed of two or more elements. They can only be separated or broken down into its individual elements or smaller compounds by chemical means. Therefore, the answer is a test tube of zinc oxide.