Considering the definition of molar mass, the number of moles of chlorine present in 140 grams of chlorine gas is 1.975 moles.
The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.
Next, you can apply the following rule of three: If by definition of molar mass 70.9 grams are contained in 1 mole of Cl₂, 140 grams of the gas are contained in how many moles?
amount of moles= 1.975 moles
Finally, the number of moles of chlorine present in 140 grams of chlorine gas is 1.975 moles.
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A) Roger is incorrect. The melting wax is a physical change but there is no chemical change taking place.
B) Roger is correct. Lighting the match is a chemical change and burning the candles is a physical change.
C) Roger is correct. The melting wax is a physical change and the burning candle wick is a chemical change.
D) Roger is incorrect. Only a chemical change is taking place as evidenced by the light and heat of the burning candles.
Melting of wax is a physical change and chemical change is the burning of candle.
Chemical changes are those changes by which composition of the original matter changes and physical changes are those changes by which only appearance of the matter changes.
In the given activity:
Hence, Roger is correct ie. The melting wax is a physical change and the burning candle wick is a chemical change.
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Answer:
The correct answer is option A. "a mineral or metal with economic usefulness".
Explanation:
An ore is defined as a rock or sediment found in nature which contains a mineral or metal with economic usefulness. The minerals or metals in the ore must be extracted before they could be used, and typically, they are refined via smelting. The ore grade is defined according to the concentration of the mineral or metal beneath the rock or sediment.
Answer:
To balance the chemical equation, I'll assume the reaction is carried out under standard conditions. Here's the balanced equation:
2 N2 (g) + 5 O2 (g) → 4 H2O (l) + 4 NO3- (aq)
Explanation:
To balance the number of nitrogen (N) atoms, we need 2 nitrogen molecules (N2) on the left side. This gives us a total of 4 nitrogen atoms on the left side.
To balance the number of oxygen (O) atoms, we need 5 oxygen molecules (O2) on the left side. This gives us a total of 10 oxygen atoms on the left side.
On the right side, we need 4 water molecules (H2O) to balance the hydrogen (H) atoms. This gives us a total of 8 hydrogen atoms on the right side.
Finally, to balance the oxygen (O) atoms on the right side, we need 4 nitrate ions (NO3-) since each nitrate ion contains one nitrogen and three oxygen atoms. This gives us a total of 12 oxygen atoms on the right side.
Now the equation is balanced with 4 nitrogen atoms, 10 oxygen atoms, 8 hydrogen atoms, and 4 nitrate ions on both sides.