Answer:
D. 18.7 grams
Explanation:
The coefficients are the key.
Create a proportion with them, and the molar mass, and then solve for x:

His measurements are precise since his pH values are close to each other in a way that it was repeated in all measurements. On the contrary to accuracy, it is the closeness to the actual pH value he should have achieved. Therefore, Jose's results are precise but not accurate since his value is not close to the actual value of pH 4.
The reaction formula CH4 + 2O2 → CO2 + 2H2O shows the oxidation of 1 mole of CH4 (Methane) will yield 1 mole of CO2 (Carbon Dioxide). Since 1 mole of CH4 will weigh 12g (for the Carbon) + 4g (1g for each Hydrogen) = 16g, then 32g of CH4 will correspond to 32g / 16g/mole = 2 moles. Therefore the oxidation of 2 moles of CH4 will yield 2 moles of CO2.
7. Tungsten is a conductor, the rest listed are insulators.
8. Thermal Energy
Not sure how in depth or what level of particles but I will go as deep as I know. The matter that makes up the world is comprised of 12 particles which are known as fermions. There are 12 fermions which are made up of 6 quarks (up, charm, top, Down, Strange, Bottom) 3 electrons (electron, muon, tau) and three neutrinos (e, muon, tau). Technically, only the up quark, down quark, electron, and electron neutrino are necessary to create all known matter since others would simply be very unstable and decay into those particles. The other type of particles are known as Bosons. These particles transmit forces and all sorts of different interactions. I have included a photo from online which describes the main characteristics of each elementary particle.