Answer:
The answer is rather simple, if you understand electron configurations: the shape of the periodic table mimics the filling of the subshells with electrons. The shape of the periodic table mimics the filling of the subshells with electrons. ... The next two electrons, for Li and Be, would go into the 2s subshell.
Explanation:
The right answer is D - mass.
Answer:
Q = -33.6kcal .
Explanation:
Hello there!
In this case, according to the equation for the calculation of the total heat of reaction when a fixed mass of a fuel like ethane is burnt, we can write:

Whereas n stands for the moles and the other term for the enthalpy of combustion. Thus, for the required total heat of reaction, we first compute the moles of ethane in 3 g as shown below:

Next, we understand that -337.0kcal is the heat released by the combustion of 1 mole of ethane, therefore, to compute Q, we proceed as follows:

Best regards!
Answer:
0.719 moles of NH₃
Explanation:
Molar mass of ammonia 17 g/mol
Mass of amonia = 12.23 g
Mass / Molar mass = Moles
12.23 g / 17 g/mol = 0.719 moles
Three classes: 28×3=84 students
8 test tubes per student: 84× 8= 672
hope this helps!