Answer:
it lost 900J of energy I will assume and that would mean the change in energy is -900J
Explanation:
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<u>Answer:</u> From the given gases, the greatest rate of effusion is of 
<u>Explanation:</u>
Rate of effusion of a gas is determined by a law known as Graham's Law.
This law states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of the molar mass of the gas. The equation given by this law follows:

It is visible that molar mass is inversely related to rate of effusion. So, the gas having lowest molar mass will have the highest rate of effusion.
For the given gases:
Molar mass of 
Molar mass of 
Molar mass of 
Molar mass of 
Molar mass of 
The molar mass of methane gas is the lowest. Thus, it will have the greatest rate of effusion.
Hence, the greatest rate of effusion is of 
So first find the moles of the H₂SO₄: Mass = Moles x RFM
so mass = 5.25 x 98 = 514.5g of <span>H₂SO₄</span>
so to find how many Liters of solution use:
Volume = Density x Grams of solute (per kg +1000)
density = 1.266 x 514.5 +1000 = 1917.357kg/l
now use equation: Conc. = Moles / Volume of solution to find the conc.
Conc. = 5.25 x 1917.357 = 4.39Mol⁻¹
Hope that helps