Answer:
Part A: 
to two significant figures
Part B: 
to two significant figures
Part C: 
to two significant figures
Explanation:
Given that :
mass of the hydrogen = 0.30 g
the molar mass of hydrogen gas molecule = 2 g/mol
we all know that:
number of moles = mass/molar mass
number of moles = 0.30 g /2 g/mol
number of moles = 0.15 mol
For low temperature between the range of 50 K to 100 K, the specific heat at constant volume for a diatomic gas molecule = 
For Part A:
to two significant figures
Part B. For hot temperature, 
to two significant figures
Part C. For an extremely hot temperature, 
to two significant figures
Answer:
C. The facial feedback theory
Explanation:
The facial feedback theory as postulated by William James and connects back to the famous Charles Darwin talks about how facial expressions stimulate our emotional state of being. Based on this theory, the emotional experiences we have are determined by the looks on our faces.
According to the question, smiling at an event makes you enjoy it is an example of what the The facial feedback theory is explaining. Furthermore, smiling, which is a facial expression causes or stimulates an emotional state of enjoyment in that event.
Answer:
X: Low potential energy
Y: High Potential energy
Z: Flow of electrons
Explanation: From the figure, it's obvious that Z is the flow of electrons, as shown by the arrow demonstrating the direction of the flow. Because of this, we can easily nullify choices B and C.
From the figure, we can notice that Y has more energy stored and X has a lot less, so you can conclude that Y has high potential energy while X has low potential energy.
Answer:
Single Compound
Explanation:
A synthesis reaction takes two or more reactants and reacts chemically to turn them all into one substance.
An example of a synthesis reaction is the reaction that takes place between sodium (Na) and chlorine (Cl) to create table salt.
