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Given :
Volume of NaCl solution 2.5 L .
Molarity of NaCl solution is 0.070 M .
To Find :
How many moles are present in the solution.
Solution :
Let, n be the number of moles.
We know, molarity is given by :

So,

Therefore, number of moles of NaCl is 0.175 moles.
The sun generates its energy by nuclear fusion of hydrogen nuclei into helium.
Answer :
the amount of heat,in joules, required to increase the temperature of a 49.5-gram sample of wanted from 22°c to 66°c is 9.104 Joules.
Explanation:
The answer can be calculated using the formula
Q = mCрΔT
where
Q is the amount of heat required in joules to raise the temperature.
m is the mass of the sample in Kg.
Cp is the specific heat of the sample in J/Kg°C.
ΔT is the change in temperature required.
Here, m = 49.5-gram = 0.0495 kg
Cp = 4.18 J/Kg°C (for water)
T₁ = 22°C ; T₂ = 66°C
ΔT = 66 - 22 = 44
Substituting values in Q = mCрΔT
Q = (0.0495)(4.18)(44)
Q = 9.104 J