The correct answer is option b, that is, triggered by changes in the weather.
Hibernation refers to a state of lower metabolism and inactivity usually witnessed in endotherms. This condition is featured by a slow heart rate, slow breathing, low metabolic rate, and low body temperature. It assists the majority of the endotherms to thrive in the cold seasons. For example, hibernation of a bear in winters. Therefore, weather change can stimulate hibernation.
Answer: The missing coefficient is 2.
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

As in the products, there are 2 atoms of sodium, thus there will be 2 atoms of of sodium in the reactant as well. This will balance the number of hydrogen and oxygen atoms as well.
Thus the missing coefficient is 2.
-NH2 is the most favorable for the reaction
Molar mass:
Br = 79.904 g/mol
CaBr2 = 199.886 g/mol
<span>CaBr2 = 2 Br + Ca
</span>
199.886 g --------------- 2 x 79.904 g
255 g -------------------- ?? ( mass of Br )
255 x 2 x 79.904 / 199.886 =
40751.04 / 199.886 =>203.87 g of Br
hope his helps!