Answer:
Sodium reacts with the oxygen in air. It reacts vigorously with oxygen and the moisture that is already present in the air and thus catches fire.
Explanation:
Expression for the
speed is as follows.

where,
= root mean square speed
k = Boltzmann constant
T = temperature
M = molecular mass
As the molecular weight of oxygen is 0.031 kg/mol and R = 8.314 J/mol K. Hence, we will calculate the value of
as follows.

= 
= 498.5 m/s
Hence,
for oxygen atom is 498.5 m/s.
For nitrogen atom, the molecular weight is 0.028 kg/mol. Hence, we will calculate its
speed as follows.

= 
= 524.5 m/s
Therefore,
speed for nitrogen is 524.5 m/s.
Your answer is correct.
MgO(s) + H2O(l) ----> Mg(OH)2(aq)
:-) ;-)
Energy= 2381 joules
heat= Mass(kg) *change in temperature(K) * Cp
2381=0.155*(15)*Cp
Cp=1024 J/kg K