Answer:

Explanation:
The formula for efficiency is

Data:
Useful energy = 3 J
Energy input = 30 J
Calculation:

Answer:- 3333 g of solution.
Some of the question part is missing here. It would be like, "Determine the mass in grams of each NaCl solution that contains 1.5 g of NaCl.
(i) 0.045% NaCl by mass
Solution:- 0.045% NaCl by mass means 0.045 g of NaCl are present in 100 g of solution. 1.5 g of NaCl would be present in how many grams of solution?
We could solve this using proportions...
(0.045/100) = (1.5/X)
0.045(X) = 1.5(100)
0.045X = 150
X = 150/0.045 = 3333
So, 1.5 g of NaCl is present in 3333 g of solution.
Answer:
1s² 2s²2p³
Explanation:
If the atom has seven electrons, it is Element 7 (nitrogen).
In the Periodic Table, you count the electrons in all the subshells up to
No. 7.
In the first Period, you have filled the 1s level (2 electrons).
In the second Period, you have filled the 2s subshell (2 electrons) and put three electrons in the 2p subshell.
Thus, the electron configuration is
1s² 2s²2p³
Note how the superscripts tell you the number of electrons in each subshell: <em>2 + 2 + 3 = 7</em>.
Answer: Fire requires oxygen to burn. Water "smothers" fire and prevents it from acquiring more oxygen. Fire also requires heat, which cool water may prevent/remove.
Answer:
73.88 g/mol
Explanation:
For this question we have to keep in mind that the unknown substance is a <u>gas</u>, therefore we can use the <u>ideal gas law</u>:

In this case we will have:
P= 1 atm
V= 3.16 L
T = 32 ªC = 305.15 ºK
R= 0.082 
n= ?
So, we can <u>solve for "n"</u> (moles):



Now, we have to remember that the <u>molar mass value has "g/mol"</u> units. We already have the grams (9.33 g), so we have to <u>divide</u> by the moles:

