<u>Answer:</u> The correct option is Option D.
<u>Explanation:</u>
Significant figures are defined as the figures that represent the digits of a number which carry an important contribution to the numerical value, starting with the first non-zero digit. For Example: 105.268 has 6 significant figures because every digit carry its own contribution towards the numerical value.
Whenever there is multiplication, the answer will contain the same number of significant figures as there are in the least precise numerical value.
Significant figures in 8.01 are 3 and that in 4.1 are 2.
So, the answer of these two numerical value will contain 2 significant figures.
Hence, the correct option is Option D.
<u>Answer:</u> The number of moles of nitrogen gas is 0.505 moles.
<u>Explanation:</u>
To calculate the number of moles of nitrogen gas, we use ideal gas equation, which is:
where,
P = pressure of the gas = 4.27 atm
V = Volume of the gas = 2.96 L
T = Temperature of the gas =
R = Gas constant =
n = number of moles of gas = ?
Putting values in above equation, we get:
Hence, the number of moles of nitrogen gas is 0.505 moles.
Taking into account the definition of molarity and the stoichiometry of the reaction, the correct option is option C) 0.44 L of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid.
The balanced reaction is:
H₃PO₄ (aq) + 3 NaOH (aq) → Na₃PO₄ (aq) + 3 H₂O(aq)
Then, by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:
Molarity is the number of moles of solute that are dissolved in a given volume.
Molarity is determined by:
Molarity is expressed in units .
In this case, 0.42 L of 2.39 M phosphoric acid reacts. So, by definition of molarity, the number of moles that participate in the reaction is calculated as:
Solving:
number of moles of phosphiric acid= 2.39 * 0.42 liters
number of moles of phosphiric acid= 1.0038 moles ≅ 1 mole
Approaching 1 mole of the amount of phosphoric acid required, then by stoichiometry of the reaction, 3 moles of NaOH are necessary to react with 1 mole of the acid.
Then by definition of molarity and knowing that 6.9 M NaOH is needed, you can calculate the necessary volume amount of NaOH by:
Solving:
6.9 * volume= 3 moles
volume= 0.44 L
The correct option is option C) 0.44 L of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid.
Learn more about molarity with this example: <u>brainly.com/question/15406534?referrer=searchResults</u>