Answer: -
The hydrogen at 10 °C has slower-moving molecules than the sample at 350 K.
Explanation: -
Temperature of the hydrogen gas first sample = 10 °C.
Temperature in kelvin scale of the first sample = 10 + 273 = 283 K
For the second sample, the temperature is 350 K.
Thus we see the second sample of the hydrogen gas more temperature than the first sample.
We know from the kinetic theory of gases that
The kinetic energy of gas molecules increases with the increase in temperature of the gas. The speed of the movement of gas molecules also increase with the increase in kinetic energy.
So higher the temperature of a gas, more is the kinetic energy and more is the movement speed of the gas molecules.
Thus the hydrogen at 10 °C has slower-moving molecules than the sample at 350 K.
Answer: D. 19.9 g hydrogen remains.
Explanation:
To calculate the moles, we use the equation:
a) moles of 
b) moles of 
According to stoichiometry :
1 mole of require 1 mole of
Thus 0.0787 moles of 
require=
of
Thus is the limiting reagent as it limits the formation of product and acts as the excess reagent. (10.0-0.0787)= 9.92 moles of are left unreacted.
Mass of 
Thus 19.9 g of remains unreacted.
E=hf
h=6.63*10^-34
f=8.66*10^14
E=6.63*10^-34*8.66*10^14=57.4*10^-20 joules
