Answer:
D. length × width
Explanation:
eg. 30 cm(length) × 20cm(width) = 600cm²
Answer:
a. CO2 and H20
Explanation:
Chemically, this combustion process consists of a reaction between methane and oxygen in the air. When this reaction takes place, the result is carbon dioxide (CO2), water (H2O), and a great deal of energy. The following reaction represents the combustion of methane:
CH4[g] + 2 O2[g] -> CO2[g] + 2 H2O[g] + energy
One molecule of methane, (the [g] referred to above means it is gaseous form), combined with two oxygen molecules, react to form a carbon dioxide molecule, and two water molecules usually given off as steam or water vapor during the reaction and energy.
Answer:
1 is the same 3 is pure substance 4 is different
Explanation:
not sure about 2
The question is incomplete, here is the complete question:
Calculate the mole fraction of the ionic species KCl in the solution A solution was prepared by dissolving 43.0 g of KCl in 225 g of water.
<u>Answer:</u> The mole fraction of KCl in the solution is 0.044
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
.....(1)
Given mass of water = 225 g
Molar mass of water = 18 g/mol
Putting values in equation 1, we get:
Given mass of KCl = 43 g
Molar mass of KCl = 74.55 g/mol
Putting values in equation 1, we get:
Mole fraction of a substance is given by:
Moles of KCl = 0.577 moles
Total moles = [0.577 + 12.5] = 13.077 moles
Putting values in above equation, we get:
Hence, the mole fraction of KCl in the solution is 0.044
<h3>
Answer:</h3>
1.001
120.0
<h3>
Explanation:</h3>
Significant figures are used in science to determine the precision of a number. Depending on the decimal point, sig figs are counted in different ways.
Decimal Points
When counting sig figs, you always start at the first non-zero number. However, sometimes you start from the left, other times the right.
- If the decimal point is present, start counting sig figs from the left.
- If the decimal point is absent, start counting sig figs from the right.
Remember to start counting at the first non-zero number.
For people in the Americas, there is a trick to remembering this.
- If this decimal is Present, start from the Pacific. If it is Absent, start from the Atlantic.
This works because the Pacific ocean is to the left of the Americas, and the Atlantic is to the right.
4 Significant Figures
The number 1.001, has 4 significant figures. Since there is a decimal point, we start counting from the left. The first digit is not zero, so we count all four places as significant.
The number 120.0 also has 4 sig figs. Like the number above, we start counting from the left because of the decimal. The first digit on the left is not zero, so we once again count all 4 digits as significant.