Answer:
3 valence electrons
Explanation:
Because aluminum has three, that means three fluorines can bond. The make the formula AlF3, also known as aluminum trifluoride. Each of the fluorine atoms gets an electron to fill their shell, and the aluminum loses three, giving it a filled shell too (remember, aluminum has three extra electrons).
Answer:
0.019 g.
Explanation:
- Firstly, we need to find the no. of moles of oxygen gas:
- We can use the general law of ideal gas: <em>PV = nRT.
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where, P is the pressure of the gas in atm (P = 1.02 atm).
V is the volume of the gas in L (V = 15.0 L).
n is the no. of moles of the gas in mol (n = ??? mol).
R is the general gas constant (R = 0.0821 L.atm/mol.K),
T is the temperature of the gas in K (T = 28°C + 273 = 301.0 K).
∴ n = PV/RT = (1.02 atm)(15.0 L)/(0.0821 L.atm/mol.K)(301.0 K) = 0.62 mol.
- To find the mass of oxygen gas, we have:
<em>no. of moles = mass/molar mass.</em>
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∴ mass of oxygen = (no. of moles)(molar mass) = (0.62 mol)(32.0 g/mol) = 0.019 g.
Answer:
Explanation:
If an electron is in an excited state it can return to a lower energy level. When it does this, it loses energy. The amount of energy it loses will be equal to the difference in the energy levels it moves between. This energy is released as a photon.
Answer:
<em>The correct option is b. new species make the environment less suitable for previous ones.</em>
Explanation:
In ecology, succession can be described as the changes in a species structure over a period of time. In a community, newer species tend to have better characteristics and adaptations to survive in a community as compared to the older ones. As a result, the new species begin to take over the land and the older ones gets removed. It is due to ecological succession that climax communities are formed from pioneer species.
Answer:
B (Final mass of the metal)
Explanation:
The independent variable in this experiment is the amount of acid the scientist pours on the metal, and the only variable in the list dependent on the amount of acid poured on the metal is the final mass of the metal. Therefore, the final mass of the metal is the dependent variable in the experiment.
