Answer:
0.0321 g
Explanation:
Let helium specific heat 
Assuming no energy is lost in the process, by the law of energy conservation we can state that the 20J work done is from the heat transfer to heat it up from 273K to 393K, which is a difference of ΔT = 393 - 273 = 120 K. We have the following heat transfer equation:
where 
is the mass of helium, which we are looking for:
Answer: 2.2x10^4
Explanation: in a adiabatic process pV^y = constant.
So V2=3V1 and p2 = p1 / 3^1.67 = 2.2x10^4 Pa
Answer:
A. I and V
Explanation:
According to Le Chatelier's Principle, increasing the product side will cause the equilibrium to shift back towards the reactant side, so I is true. By the same principle, II is false.
For gases, decreasing the pressure will cause the equilibrium to shift towards the side with higher number of moles. So V is true.
The reaction is endothermic, so increasing the temperature will shift the equilibrium to the products, so IV is false. And adding a catalyst has no effect on the equilibrium, so III is false.
For a concave mirror, the radius of curvature is twice the focal length of the mirror:
where f, for a concave mirror, is taken to be positive.
Re-arranging the formula we get:
and since the radius of curvature of the mirror in the problem is 24 cm, the focal length is
