Answer : The molar mass of the unknown gas will be 79.7 g/mol
Explanation : To solve this question we can use graham's law;
Now we can use nitrogen as the gas number 2, which travels faster than gas 1;
So, 167 / 99 = 1.687 So the nitrogen gas is 1.687 times faster that the unknown gas 1
We can compare the rates of both the gases;
So here, Rate of gas 2 / Rate of gas 1 =
Now, 1.687 = square root [
]
When we square both the sides we get;
2.845 = (molar mass 1) / (28.01 g/mol N2)
On rearranging, we get,
2.845 X (28.01 g/mol N2) = Molar mass 1
So the molar mass of unknown gas will be = 79.7 g/mol
Explanation:
Upon dissolution of KCl heat is generated and temperature of the solution raises.
Therefore, heat generated by dissolving 0.25 moles of KCl will be as follows.

= 4.31 kJ
or, = 4310 J (as 1 kJ = 1000 J)
Mass of solution will be the sum of mass of water and mass of KCl.
Mass of Solution = mass of water + (no. of moles of KCl × molar mass)
= 200 g + 
= 200 g + 13.625 g
= 213.625 g
Relation between heat, mass and change in temperature is as follows.
Q = 
where, C = specific heat of water = 
Therefore, putting the given values into the above formula as follows.
Q = 
4310 J =
Thus, we can conclude that rise in temperature will be
.
Answer:first D. 88L
Second A 2*10^24
Explanation:
At stp 1 mole = 22.4L
mw Cl2= 70.9
280 g =280/70.9 moles, about 4
4*22.4 = about 88
aw Sr 87.6 —> 6.02214076*10^23 atoms = 1 mole
Answer:
6.70 grams of krypton-81 was present when the ice first formed
Explanation:
Let use the below formula to find the amount of sample

where

here
t = 458,000 years
= 229,000
= \
n =
= 2.000
Now substituting the values



